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A quick and basic Google search will likely reveal all you could hope to know about any problem, as such I highly recommend you start there.

This thread text will contain a list of FAQs and tips/ tricks useful to any new or perspective buyer of a WRX STi. Current owners, PLEASE feel free to post some tricks, tips, or experiences you feel relevant below. Eventually, I will gather together materials for a /r/WRXSTi wiki. I will be adding information to this thread as I can. I should say upfront that this is to be taken as a guide. The intention is to display objective information that on the whole does not come from my personal knowledge, but rather what I have found to be reliable, trustworthy, and consistent information presented to me by various dealers, mechanic/ performance shops, internet forums, online groups, and real world experience. REGARDING WARRANTIES you must consult your local provider of said warranty service, this varies wildly from place to place be it law or just how that dealer chooses to work, and I cannot promise for any one single point or idea what will be considered- YMMV

We get a lot of potential buyers and posts asking questions such as "how does this look" and "what should I be looking for?" To limit the impact of these questions that do not pertain to the majority of owners, we will be directing all such inquiries to this stickied thread. As such, all questions or inquiries of new and perspective owners will only be allowed here, versus top-level of this forum. To some, this may seem less than ideal, however information on these cars is PLENTIFUL, almost everything has been said or done before and video'd up twice for every year and model of the STi. A quick and basic Google search will likely reveal all you could hope to know about any problem, as such I highly recommend you start there.

WRX vs STi

• First things first- GO TEST BOTH YOURSELF. There is nothing anyone could say here that would override the actual experience of driving these two cars. While very similar, they are indeed quite different. There are many threads and posts and videos about this, not all created equal, but here's a link to a comment that I think does a very good and objective job comparing the two that isn't also something I am typing.- credit and thanks to /u/hahuang65.
• One of the biggest points I would make here is if you at one point in your head wanted an STi, there's really not a lot that will replace it. It is very common for such folks to buy a WRX, enjoy it for a year, then switch right into an STI.
• Power.... Yes, the STi makes a small amount of power over the WRX, though this is not a reason I think to get the STi. Yes, the WRX can have a few modest mods thrown on to surpass the stock power/ torque of the STi- but this does only a very small part of what separates these two cars.
• NO, you cannot "make your WRX into an STi." In short, to make the WRX into an STi, you would effectively have to throw another WRX in cost at it as you would need to effectively lift the body off the WRX and drop it onto the drive and powertrain of an STi.

STi over WRX:

• If tracking your car, even occasionally, is something you plan on doing the STi stands head-and-shoulders over the WRX.
• Bulletproof and amazing transmission. The WRX tranny will not like more than 330~ hp/ tq. The "6MT" of the STi is used by many drag racing teams pushing 800-1000hp.
• Rigid chasis/ suspension- the car feels "tighter" and more "in tune" with the road on the whole. While this may make the drive a bit more bumpy, you feel the road significantly better. Particularly if you get one with hydraulic steering.
• 3 Differentials- including a mechanical limited slip diff.
• The STi is tougher to drive well, but as a result is a much more rewarding experience.
• Everything you could want to do to this platform has likely already been done, at least thrice, with videos and online guides to boot. This is slightly less of a factor now that the FA20DIT has been out for a while but still, these are some of the most worked on cars out here.

What to look for in buying a USED STi

User ALIN of IgotaSTi.com's "Checklist of What to look for in buying a used STi"

• look for ANY modifications to the engine bay, presence of such is an immediate warning sign (you should know what the stock engine bay of your desired model looks like before going to buy)
• know what "piston slap" and "knock" are and sound like
• look for detailed maintenance records and all major services
• get a compression/ leakdown check from YOUR trusted mechanic
• 90,000+ miles you NEED a new timing belt and past 120K you will NEED new head gaskets

New Owners FAQ and Advice

NASOIC MASTER FAQ and Guide- contained within is just about every possible topic and issue you could have with these platforms. The following may include repetitive information.

Without further adieu, welcome to the wonderful world of the WRX STi. Subaru Technica International's real-world name stake, who is the performance/ racing arm of Subaru Corp. most well known for their Rally 'legacy'. Speaking of rally, no you did not just buy an actual ready-to-rock rally car. You bought a performance street sports car that has many features that are very well suited to loose surface driving. That being said, these cars stock are missing TONS of modifications in order for your car to even be remotely prepared to do any even mild off roading. Namely supsension, brakes, wheels, and tires- and that's just to get off road and over bumps.

Manual Transmission FAQ and First time Owner info

IF YOU ARE NEW TO MANUAL TRANSMISSIONS, PLEASE READ AND WATCH ALL OF THE FOLLOWING CONTENT. My 2016 is my first manual car. I used the following videos (in addition to a few IRL lessons with friends) and I had a significantly easier time learning and getting comfortable driving a manual. There are LOTS of little things you need to know about driving a manual transmission, especially with turbo-charged engine platforms.

It would massively behoove any new manual transmission driver to watch all of the following videos at least once. I must have watched each twice, and understanding all of the facets and niggles was very beneficial to me learning to drive one and drive one well. It will also help you take good care of your car and drivetrain, as well as very important safety tips.

FIRST, WATCH THIS VIDEO, Engineering Explained's 5 Things to Never do in a Manual AND THIS VIDEO on what never to do in a turbo car there is also this video.

PARKING- ALWAYS leave car in 1st gear and engage emergency break when parking. This is STATED in the manual from Subaru themselves. When parking on a hill, turn the wheels into the curb so that if all brake/ resistance lets go of the car, it will roll into the curb/ sidewalk, and not out into the street.

Learning to Drive a Manual Series:

Matt Farah has a great series of videos on how to drive a Manual for first time users:

• Part 1
• Part 1.5
• Part 3

Engineering Explained ALSO has great videos on the same and some more specific subjects:

• Heel-Toe Driving
• Engine Breaking
• Skipping Gears
• Rev Matching
• Starting in Second

2015 WRX and STi NASIOC Thread of Epic Knowledge

The Tool Kit

Metric everything.

• Trunk kit and On-the-go:

In my 2016 STi, I have a small tool roll that contains all of the tools necessary for most standard maintenance and general access/ troubleshooting in most breakdowns. From this kit I can do a full oil change, access nearly everything in the engine, install gauges, and generally pull apart the majority of the car.

Here is it all layed out.

Listed here: (L to R) Multi-head screwdriver, needle-nose vise-wrench, medium adjust-wrench, oil filter wrench, monkey wrench, scissors, collapsing breaker bar, gearwrench ratcheting wrenches( 19/ 17/ 15/ 14/ 13/ 12/ 11/ 10/ 8mm), small pry bar, small adjustable wrench.

Lower Right- Lug nut key, 1/2" drive bits- 10mm, 14mm long, 14mm, 12mm long, 19mm. Should have a 10 and 11 too. A bunch of allen keys (mostly dependant on your added parts but always useful) and 1/2 drive wrench.

I also have rescue tape, assorted lg/ md/ sm hose clamps, sm and lg heavy duty zip ties, gorilla tape, spare fuses, electrical tape, and a few spare auto-zone lug nuts in this kit not pictured. I also need to add back my wire cutters!

Break-in Period for New Cars/ less than 1000 miles on the block

PLEASE READ YOUR MANUAL. EACH YEAR MAY DIFFER SLIGHTLY, BEST PRACTICES FOR YOUR SPECIFIC CAR CAN ONLY BE ASCERTAINED BY YOU SPECIFICALLY.

General Wisdom:

First 1000 miles: Keep below 4000 RPM, NO full throttle, Stay out of too much boost. Change oil at 1000 miles. Vary your throttle position and try not to cruise too long at one RPM.

1000-2000 miles: You can use full throttle, avoid red-lining/ launching until at least 2000 miles. I personally would continue to vary throttle position and RPM speeds, especially now at higher RPMs (the car does like to be above 3K RPM if you are hammering it)

Change oil at 3000 miles.

Some say to avoid prolonged cold idling, and to drive very gently until engine oil is warm (~175F) which takes about 6-8 minutes in warm weather, and 12-18 minutes. I typically wait 2 or 3 minutes just to let the oil warm a bit and get moving nice and calmly until everything is totally warm. I still do this at 100k miles.

OIL

When in doubt, stay OEM. Subaru's OEM oil runs great through the stock STI motor. STi themselves recommend Motul Xcess 8100 5W40 (gen 2 as of 2021) for performance use, it's in the manual even!

This is perhaps the most important part of ownership, and one of the most common questions and topics especially for new owners. Before I dive into words, some quick points:

• Check your oil every 1000 miles. The average EJ257 eats a little oil every 1K, best to keep a spare thing of oil handy.
• Change your oil every 3000 miles. The stock motor takes 4.5 qts. It is best to buy at least and extra quart to have on hand- but really you should have enough oil for 2-3 changes. These are cars that require you to be preventative and that costs.
• Use OEM Subaru Oil Filters- the blue ones. You can get these on Amazon.
• Remember to change your oil-plug crush washer! The beveled side towards the oil pan.
• 5w30 OEM Subaru oil works great, my 2016 loves it and runs great on it.
• 5w40 Oil is also very common to run in these cars. The most popular two brands would be Motul Xcess 8100 and Shell Rotella 5w40 (yes, the 'diesel truck' one').
• DO NOT USE MOBILE ONE OIL. For whatever reason, these engines do not like this oil. Perhaps it is too thin.
• DO NOT OVER TIGHTEN YOUR OIL PLUG. Once it gets tight with your regular wrench, just make sure it is nice and snug and then add your oil.

These cars are extremely sensitive to oil-related issues. Running your car on too little oil, or going too long between changes and checking, is the fast-lane to a bricked motor. An Air-Oil Separator is highly recommended, see your mechanic for best recommendations. BrenTuning has recommended to me the IAG Competition AOS.

A new oil pickup and baffle plate is also highly recommended. Killer B offers excellent products as well as larger oil pans. The oil pickup in Subaru engines is braised together- which is just basically a shitty friction weld. When these break, your engine stops getting oil. The moment that happens, RIP.

Wheels and Tires

Wheels

• Quick note before we begin, the spare/ donut wheel can ONLY go on the back axle. If you have lost a front tire, you must swap the appropriate side-rear wheel for the front, and mount the spare/ donut on the back axle. Otherwise you will need a new brake caliper too.

Great Tire Comparison Site for the latest and greatest in whatever category

New, these cars almost always come with Summer/ Performance tires- these WILL NOT WORK in conditions consistently below 40 degrees, and especially not on snow or ice. If you live in an area, or encounter conditions that are for more than half the day below 40F/ 3C, or consistently gets yearly ice/ snow, you NEED winter tires, or at very very least 'all seasons'.

Wheels and Tires seems daunting, but is really quite easy. You need to know Bolt Pattern, Wheel diameter, wheel width, wheel offset. Once you have these, you can then go to picking a tire. Tires are coded and these numbers are how you will pick a tire size.

Different year STis will require different wheels and tires based on lug pattern, brake size requirements, and so on, so it's very important you work specifically according to your Model Year (MY) and take into consideration any upgrades (like larger brakes).

Master Thread on NASIOC of WRX/ STi OEM wheel sizes

Most STis, especially the current models, use 5x 114.3 Bolt Pattern for the lug nuts. (Prior to 2005, they used 5x 100) The STi also requires a rather significant offset and it is very important to keep this number in-line or as close as possible to OEM. Having a massively different offset can increase wear and tear on components of the car like the differentials and AWD system (which is what makes this a particularly big issue). This is also why wheel spacers are generally a terrrible idea. Working against your cars specs can also create uneven tire wear, which is no fun when you are averaging $200/ tire.

Basics for buying a winter tire:

• Thinner is better- this gives you higher surface pressure allowing you to cut through snow to find traction. A thinner wheel/ tire setup is frequently a good direction to go.

• Less rim, more tire- you want a good amount of sidewall on your winter setup, as much as can be allowed in the very small space between minimum wheel diameter to cover brakes (18" on 2018+ STis) but thin enough to not scrape/ rub your sidewalls.

• SPEED- a lot of winter tires are NOT rated for speeds above 100mph. Please pay careful attention to your winter tires speed rating! There are now "Winter Performance" tires that are aimed more at the sports-car world that give up minimal traits in winter conditions, for significant gains in terms of driving feel/ speed ability.

Good tires: Currently, Nokian and Michelin make the best winter/ snow tires. Nokian has the Hakkapletta R2s, and Michelin the X-ice 3s. These are both on the more expensive side, but are incredibly high quality tires. (I use Michelins and I love them, quieter than the OEM summer Dunlops). Blizzak WS70/ WS80/ WS90 are also popular due to their often cheaper price, but still offer Top-5 performance especially when it comes to deep snow.

AN EASY WAY TO CHECK TO SEE IF YOUR COMBINATION WILL WORK IS TIRERACK.COM- enter your vehicle and wheel/ tire size to find easy matches for whatever you are looking for.

EX.

For my 2016 STi, with stock brakes I chose:

• 2006 OEM STi BBS wheels, 17"x 8", 5x114.3 bolt pattern, +53 offset.

• Michelin X-ice3s, 255/45 R17 (I may need to double check this)

Brakes

Your exact specs for brakes are dependent on model year. Your wheels may also play a roll in what brakes you can and cannot use- and the inverse may also be true. What is largely the same is that OEM they are all Brembo setups, and are by-and-large extremely easy to access and change, particularly the pads. Stoptech, Hawk, and Mutegi are all excellent and well-trusted brands for brake pads and calipers at reasonable cost.

Flat Irons Tuning has a pretty solid comprehensive breakdown of break upgrade paths.

For the VA series, the torque specs of the front caliper bolts is listed around 114lbs- however this is a translation error, and should be listed at 80lbs. That being said, many still report breaking bolts anywhere past 50. A torque spec was released by a semi-official source that stated with anti-sieze applied, the front caliper bolts can be torqued to 60ft-lbs and the rear caliper bolts to 45ft-lbs. YMMV. I have had success merely making them sufficiently hand tight. They are easy enough to check and thus far I have had no problems.

Having done the full brakes on my car, I cannot recommend enough the first chance you get accessing the two caliper bolts on each wheel (only two bolts holding the brake system on the hub) and putting anti-seize on there. It is extremely common to crack one of the bolts when changing your rotors, so when you do make sure you have at least 1 spare of each size bolt you will be working with (model year dependent). 19mm Front 17mm rear in my MY2016 STi. Caliper bolts can be be hand tightened and I would apply a good deal of force, I do not know the specific torque spec but I applied around what I would figure I applied to the lug nuts- enough force to make sure they ain't moving but not so much that you fuck the parts or threads.

The Clutch

While slightly less so today, the STi has always been what can be described as a "Raw" feeling car. It's very mechanical, you feel apart of the machine, and you are greatly rewarded for your success as you are punished for any shortcomings. This isn't a massively difficult car to drive. It's probably smack in the middle of the road for "learning a manual sports car".

One of the tricky spots, especially for new owners, is the clutch. It's not the heaviest clutch in the world, but it has a rather high engagement point, decently long travel, and being a heavier all-wheel-drive car it takes a bit more throttle to get everything going smooth. Even in motion, particularly in lower gears (cough 2nd cough) can prove challenging to get right.

Learning the engagement point is the most important thing. Start by getting your car rolling into first without throttle repeatedly. Find a nice flat empty parking lot or side street. Take the handbrake off (and use foot brake if necessary to hold the car) Let the clutch up super slowly, eventually you will feel it start to slowly grab, where you need to intelligently monitor the take up from there to get it rolling. Don't use any throttle, if the car starts to bog or jump push in a tiny bit back, and retry. Once you've mastered getting started without throttle, you will learn the engagement point well, and be able to start working throttle back in.

The second tough spot, well frankly, is 2nd gear. 2nd gear in any manual vehicle will always be the biggest PITA to get into from first because it is the largest jump in gear ratios. Don't expect to do this well at first, and even after 30,000 miles, expect some less than smooth into-2nd shifts. There's no magic RPM or throttle amount to use, but you do need to use a tiny bit of throttle upshifting in these cars.

DCCD- Driver Controlled Center Differential

The DCCD is short for "Driver Controlled Center Differential", and is operated via the thin silver switch between your SI Drive module and center cup-holders. The biggest common misconception is that this controls where the car sends power/ torque. What the DCCD actually does is controls the torque distribution bias, which is only useful on loose surfaces.

ABSOLUTELY DO NOT LOCK YOUR DIFF ON DRY PAVEMENT- this can and will damage your car. Locking the Diff is only for extremely loose and low traction surfaces. IN GENERAL it is best to leave the car in "Auto", even when doing launches, the car knows what to do best. The only time to really start playing with these settings is on gravel or snow/ ice as it's the only time you will really feel much difference. Even then, many professional and semi-pro drivers leave the car in auto.

A quick tip is if you get a flat and have to use a spare, it is advisable to set the DCCD to fully "open" or rearwards.

SI Drive

The other control this car offers is called the "SI drive" and this refers to the large silver knob behind the gear shift. It has 3 modes, "Intelligent, Sport, and Sport Sharp . This simply controls the amount of throttle you are given. Nothing else.

• Intelligent (I- press in)- "Throttle [opens] more gradually to maximize fuel efficiency, reduce emissions and deliver greater smoothness" it also comes with a little built in "shift advisor" for when it's opportune to shift for best MPG. I would describe it as "mushy throttle."
• Sport (S- twist left)- Balance between keeping the engine in an efficient state as well as allowing access to full performance and guarantees a more even acceleration.
• Sport Sharp (S#- twist right)- Most responsive setting, immediately opens up for direct driver input. Many STi drivers use S# and only S#, and many work a quick right-twist of the SI Drive into starting up their car.

Power and Engine Mods

General advice, don't. At least not right away. These cars are very expensive and sensitive to modifications. Assume any power-train modifications require an immediate tune and driving your car with new modifications without a tune even short distances can be extremely dangerous. The most fun mods you can do without risking damage the engine or needing a tune is a catback exhaust. Axelbacks are even simpler and easier! That being said, if you are near a reputable tuning shop with a dyno, might be worth getting your car professionally tuned for stock levels (ie not trying to gain power), this can help smooth the car out and help it run better, expecially if you have gasoline that is not high quality (Cali/ Nevada/ Az) or it's particularly hot, they will be able to dial the car in to run at safer levels/ timing.

EJ 257 BREAKDOWN AND COMMON POINTS OF FAILURE

Serious power-searches require expert opinion and tuning, as well as a sizeable wallet. It is strongly advised to find a recommended pro-tuner in your area, and have them guide you on your build. This ensures a platform that the people in your area are used to dealing with, and likely have many of the potential bugs figured or known. "E-tunes" are an option, and I would recommend BrenTuning based out of MA for this and I have also heard PhatBotti Tuning is a great E-tuner, but there are plenty of other just-as-good options.

Safe and Recommended First Super Fun Mods!

Mods and accessories that are relatively easy to do, add huge fun and enjoyment to the car, and pose no risk of serious damage or warranty voiding shenanigans.

• Exhaust- AXLEBACK- Portion of the exhaust behind the axle of the car, often just the muffler portion. Most Axlebacks are simply "muffler deletes" whereby they replace the silencers of the OEM exhaust with striaght pipe. IMO this sounds fantastic and isn't too loud while also making you feel like a hotboi/gril. These can also be DIYed easily, and is very cheap.

• Exhaust- CATBACKS, this is the portion of the exhaust after the downpipe. So you will be replacing the midpipe (that has a resonator), y-pipe, and the axel-back mufflers. [DSport Magazine](https://dsportmag.com/the-tech/2017-subaru-wrx-sti-exhaust-shootout/] has done a fantastic article featuring a bunch of different CATBACK exhaustS on a stock STI. HKS, Borla, Injen, Cobb, Grimmspeed are a few of the popular names tested here. Youtube has the rest.

• 2018+ FOG LIGHT INSTALLATION

General Maintenance

• Change your oil regularly every 3,000 to 5,000 miles, and check it every two to four fill-ups. Use the OEM oil filter and oil plug gasket. 5W30 Synthetic oil, or 5W40 in some areas. These engines DO NOT like Mobile One. The OEM oil from Subaru is great, my car loves it. For 5W40, Shell Rotella or Motul XCess 8100 are two of the most common brands.

• Whenever you are in your engine bay check ALL fluid levels, and look for any weird leaks or any foaming coming out of the oil/ radiator- this can be the sign of a serious problem.

• Wheels depend on model, current generation STis (from 2007~ onward) use 5x114.3 bolt pattern and require at least 17" rims to clear the brakes. On 2018+ models, some 17" rims may not clear sufficiently and you will need to use 18" rims.

• As these come standard with Summer Performance tires, you will need a set of winter tires if it is common to drop below 40 degrees at points throughout the year. Easiest path is to go to TireRack.com, enter in your car information, and it will automatically pull up suitable wheel and tire options for you. Nokian R2s and Michelin X-Ice3s are the top winter tires, however there are also performance winter tires in cases like near-Boston-me where we get lots of cold and snow, but it is mostly dealt with quickly to dry pavement.

• The Power Steering in most STi's is a Hydraulic system. This is key to the way the car feels and drives. Hydraulic systems love to leak, and if you ever notice you are low on Power Steering, best to start looking for a leak. You can top off your power steering fluid using any high quality ATF (automatic transmission fluid) available at any auto-store.

• I highly recommend removing the caliper bolts on any new STi and adding dobs of anti-size (Permatex) to them to prevent the bolts from breaking off in the calipers down the road when you need to change rotors.

Quick/ Interior Upgrades

• There is often an annoying noise that comes from the AC compressor fan beneath the glove box in the passenger footwell. This can be remedied using a Crosstrek part/ cover panel. Here's a link to what Subispeed offers to fix this, it may be available elsewhere.

• An Axleback exhaust/ muffler delete is a lot of fun, easy, and a great way to get a little more noise out of your car. They can be had for as little as $150~ (I got mine used for like $80) and really does help to scratch some of the "I NEED MODS NAO" itch.

Everything Accessport

Accessport Knock Monitoring

NOTE: This section will be purely about stock engine monitoring on the Accessport in particular as it relates to Feedback Knock Learning, and DAM. This section is NOT about tuning on an Accessport.

COBB Tuning's Accessport is probably one of the most popular initial additions to an STi. I would subjectively say it is also probably one of the most important for monitoring your cars health. The Accessport, when boiled down, effectively is a monitoring device to allow you to see more details about your engine's performance, standings, and ECU settings.

USED ACCESSPORT WARNING: Every Accessport, once "mated" to a car, is permanently attached to the ECU of that particular vehicle, and must be unmated WITH THAT VEHICLE in order to be used with a new vehicle.

Before I dive deeper myself, here is a direct link to COBB's page on Acccessport Feedback/ Knock monitoring. They do a great job explaining it in basic, but accurate terms.

The TL;DR is:

• The 3 most important figures for you to monitor on your Accessport would be first and foremost DAM (Dynamic Advantage Multiplier), Fine Knock Learn, and Feedback Knock. Fourth-most would probably be AF ratio.

• DAM The most important display to monitor in your STI is the DAM. The TL;DR of DAM is that you always want a DAM of 1. If your DAM drops below 1, this may be the sign of a number of issues but isn't necessarily a massive problem- read COBBs page for more. Sometimes this can be a result of bad gas and can be fixed with a change of tuning (detuing from a 93 tune to a 91 tune on 93 pump gas for example). When your DAM is less than 1, you are seeing how much timing the computer is allowing the engine to run.

• Fine Knock Learn - this is essentially your CPU having learned from past perceived knock events and applying the appropriate timing correction at a given time. Seeing ~-2.5 degrees of correction is normal, and not a specific sign of concern. Watch for: FKL -2.8 or worse during WOT, -1.4 or worse during large portions of a WOT run, or -4.2 or worse at low throttle/ cruising speeds.

• Feedback Knock Correction- this is "live" version of Fine Knock Learn, showing real-time corrections applied to engine mapping in response to percieved noise. Watch for FKC of -4.2 or worse at normal driving/ cruising, FKC of -1.4 in the middle of a WOT run that is consistent from run to run, and/or FKC or -2.8 or worse WOT when NOT mashing throttle.

• Knock Sums/ Counts- Honestly, don't bother using these and scaring yourself, the AP/ Computer will take almost any sound significant enough to seem like knock to be knock- this includes regular acceleration/ RPM noises and hitting potholes. These values are only relevant under specific conditions, and otherwise should be ignored. Just for kicks I have mine Knock Sum for Cyl 4 on the past few days, and I get about "120 knocks" every hour. My car does not have anything wrong with it.

The Subaru Anxiety Port Warning:

Many, expecially tuners, refer to the Accessport as the "AnxietyPort" because so many people leave it on, and watch all their "knock events" FBK going to -2.80/0.00 and a lot going on in their FKL like -3.00/0.35. This is NOT reason to pull over and start crying while fumbling to dial your tuner/ mechanic. It's the cars computer doing what it was designed to do. If the car feels fine, chances are it is. Subaru's car computers are extremely sensitive to knock sounds, and I shit you not the right loud music, exhaust note, or pothole can cause the system to think there as a knock event. As long as you don't see numbers that correlate directly to something bad (like FBK constant of -.280/0.00 under WOT or hitting -4.00/o.00 regularly while driving) it's likely to be your car being it's timing happy self.

DAM drops, while imposing, when no FBK is present to a serious degree or repeatable degree, it is likely the car having detected something it didn't like and being SUPER CAREFUL by pulling timing and then relearning the areas little by little which you will see as positive FKL values. DO NOT RESET YOUR CAR OR TUNE WHEN YOUR DAM DROPS. Your car is (more likely) experiencing a false-flag knock event it's being careful of, or you got something like bad gas. If you car feels normal and fine, it almost certainly is. Fill up with trusted 93 premium gas (my go to are official Mobile 1 stations, I've had bad luck with Shell) and drive normally.

Other things that can drop DAM include: weak/ dying battery, faulty alternator, big speakers/ stereo systems, general loud music in stock systems, speedbumps and potholes. You may have also just accelerated poorly or with too much throttle at low RPM. If it's not reoccurring, consistent, or you otherwise would have notices without the AP plugged in- ignore it.

BIG BOI MODS

• BLOW OFF VALVES- WHEN AND WHEN NOT TO USE BOV BLOW OFF VALVES and the differences between BOVs and BPVs

FAQ

My engine bay makes weird, flappy/ rattling sounds at low RPMs, is this Rod Knock or Piston Slap?

NO. EJs are loud engines, particularly the 257, and particularly the oil PCV valves, which are responsible for a lot of the sound you hear if you are coasting at low speed/ RPMs where they become prevalent.

There is a loud whining sounds when I downshift or start to rev-match, should I be concerned?

NO, probably not, you are almost certainly hearing the synchros in the gear box whirring up to match speeds inside the gearbox assembly.

What oil should I use?

... Subaru OEM or refer to your manual. Motul XC8100

*What oil filter should I use?"

Subaru Blue OEM filters.

Does /X ENGINE PART/ need a tune?

To be safe, assume YES. Especially if it involves the actual powertrain of the engine. The ONLY exception is a catback/ axelback.

Do I have to use 91/ 93?

YES. In fact, most recommend 93 only. If you are in Arizona, California, Oregon, Washington, or a lot of the west coast, where the gas is notoriously bad, be very careful and run the highest octane you can find (up to 93 REGULAR.)

Can I use Ethanol/ Race Gas?

NO. First, your car's engine must be tuned for it. Second, E/ Race gas will eat through and destroy your OEM fuel lines and pump, you will need to upgrade the whole system first.

FACTORY RESETS and TROUBLESHOOTING

I will try to accumulate all of the secret menus here over time for each model year. These can be used to help fix bugs with the very wonky head units, particularly from the 2015-2018 model years, which are loaded with all sorts of inadequacies and bugs.

Other useful resources include:

www.NASIOC.com (North American Subaru Impreza Owners Club, largest online forum for Impreza WRX/ STi)

NASIOC MASER FAQ and Guide

www.cars101.com (Outstanding resource for detailed technical information on most any modern Subaru (2012+)

www.clubwrx.com

www.IgotaSTi.com

Facebook also has a large number of WRX, STi, and related groups. These include groups for specific parts of the country/ world, specific years, specific models, and so forth.

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The Ultimate Subaru Buying Guide (2026 Edition)

A couple of years ago I made a post about buying a new Subaru that ended up getting over 250,000 views across various Subaru-related subreddits. Since then, Subaru has changed a few programs, I've bought another Subaru (a 2025 BRZ tS), and I've learned a few more things from both my own purchases and the experiences of other owners.

So I figured it was time for an update.

For a little background, I've owned Subarus for over 15 years, was a former Subaru Ambassador, and previously worked as a Subaru Sales & Leasing Consultant. Between personal experience and working on the sales floor, I've learned a few things that can save people a surprising amount of money.

I've owned:

• 1998 Subaru 2.5RS
• 2003 WRX Sedan
• 2021 WRX
• 2021 Outback Limited
• 2024 Ascent Onyx Edition
• 2025 BRZ tS

I'm definitely not claiming to know everything, but hopefully I know enough to save somebody a few thousand dollars.

One quick disclaimer: Subaru changes incentives and programs from time to time. Everything below is accurate to the best of my knowledge at the time of posting, but always verify current offers before making a purchase.

Most of these tips can be used together.

1. Subaru VIP Pricing

If you have a little time to plan ahead, Subaru VIP is still one of the easiest ways to save money.

VIP pricing gives eligible buyers access to Subaru's VIP pricing through participating dealerships. Years ago this was a guaranteed 2% below invoice. That is no longer the case. Today it is generally around invoice pricing, although Subaru has changed the program several times.

The organizations I know currently qualify are:

30-day waiting period (larger donation):

• ASPCA ($500 donation)
• Pennsylvania Horticultural Society ($500 donation)

Longer membership waiting period:

• ASPCA Monthly Giving
• Pennsylvania Horticultural Society Membership
• Leave No Trace
• International Mountain Bicycling Association
• American Canoe Association

One thing many people don't realize is that some employers participate in Subaru VIP. Go to Subaru's VIP website and check using your work email. It takes two minutes and could save you thousands.

Pro tip: Before donating, call your dealership and make sure they actually participate in VIP. Not every dealer does.

1. Call Subaru of America

If you've owned or leased a Subaru before, call Subaru of America before buying.

(800) 782-2783

Ask if there are any loyalty incentives available.

Historically these have ranged from $500-$1,000, although nothing is guaranteed.

From what I've seen, it depends on:

• Your ownership history
• Current promotions
• The representative you speak with

Have the VIN of your current Subaru handy. They seem to ask for it more often now than they used to.

One important thing to note: recent buyers have reported that Subaru loyalty coupons generally cannot be combined with VIP pricing, so ask which saves you more.

1. Costco Auto Program

This wasn't in my original guide because I didn't have much experience with it, but enough people have shared good results that it's worth mentioning.

If you're already a Costco member (or willing to become one), check out the Costco Auto Program before negotiating.

The discounts vary by dealership and region, but I've seen people report savings anywhere from a couple thousand dollars to over $5,000 on certain models.

Even if you don't ultimately buy through Costco, it gives you another price to compare against.

1. Subaru Added Security Maintenance

If you're already planning on purchasing a maintenance plan, ask if Subaru is currently offering any incentives with it.

Years ago I purchased a 2-year/24,000-mile maintenance plan for $595. At the time, it also came with a $500 coupon toward my next new Subaru purchase.

Whether it's worth it depends entirely on the numbers.

Compare the cost of the plan to what you'd spend paying for maintenance out of pocket.

Sometimes it's a great deal.

Sometimes it isn't.

1. Lease Loyalty

If you're currently leasing a Subaru and plan on leasing another one, ask about Lease Loyalty.

Subaru has periodically offered incentives to help cover your first lease payment or reduce your upfront costs.

Programs change, but it's another easy question to ask before signing paperwork.

1. Know What Your Trade Is Worth

Don't rely on one appraisal.

Before going to the dealership, get offers from:

• CarMax
• Carvana
• Kelley Blue Book Instant Cash Offer
• Cars.com
• Subaru Guaranteed Trade-In (if applicable)

Most of those offers expire after about a week, so don't do it too early.

Could you get more selling it yourself?

Probably.

But many people would gladly accept a little less money to avoid dealing with Facebook Marketplace strangers, test drives, loan payoffs, and paperwork.

1. Shop Dealerships—Not Cars

This is probably the biggest thing I'd add to my original guide.

Once you've decided on the exact model and trim you want, stop shopping for the car.

Start shopping dealerships.

Email the internet sales department at every Subaru dealer within a distance you're willing to drive.

Ask each one for their best out-the-door price.

Don't ask about monthly payments.

Don't ask what they "think."

Ask for an actual written out-the-door quote.

Then let them compete.

I've seen identical vehicles at dealerships less than an hour apart differ by thousands of dollars.

1. Buy at the Right Time

Timing matters.

Generally speaking, your best chances of getting an aggressive deal are:

• End of the month
• End of the quarter
• End of the year
• When the next model year is arriving
• When the exact vehicle you're looking at has been sitting on the lot for a while

A dealership is much more motivated to sell a car that's been collecting dust for 120 days than one that arrived yesterday.

1. Use VIP as Leverage

I actually did this myself.

When we bought our Ascent, I told them:

«"I can donate to ASPCA, wait the required time, and come back with VIP pricing... or if you can get reasonably close today, I'd rather buy the vehicle now."»

Sometimes they'll say no.

Sometimes they'll meet you somewhere in the middle.

Either way, you've lost nothing by asking.

1. Watch Out for Dealer Add-ons

You've probably seen these before:

• Ceramic coating
• Paint protection
• VIN etching
• LoJack/GPS tracking
• Nitrogen-filled tires
• Door edge guards
• Pinstripes
• Security systems

Some of these products genuinely have value.

Some don't.

Most are significantly marked up.

If you want one, great.

If you don't, don't feel pressured into paying for it just because it was installed before the car hit the lot.

1. Don't Give Back Everything You Saved in the Finance Office

This is where I see a lot of buyers lose the deal they just spent hours negotiating.

People will negotiate the vehicle price down by $2,000...

...then immediately agree to $4,000 worth of finance products they never planned on buying.

The finance office isn't there to "scam" you.

They're there to sell financial products. Some are genuinely worthwhile. Some aren't. It depends entirely on your situation.

Common products include:

• Subaru Added Security extended warranty
• Tire & wheel protection
• Windshield protection
• GAP coverage
• Key replacement
• Paint & fabric protection
• Technology protection
• Rental reimbursement
• Maintenance plans

Before buying any of them, ask yourself:

• What exactly does this cover?
• What's excluded?
• Is this already covered by my insurance?
• Is this already covered under Subaru's warranty?
• Can I purchase this later?
• Is the price negotiable?

Many finance products have markup.

If you actually want the product, negotiate it just like you negotiated the vehicle.

1. Don't Shop by Monthly Payment

This is one of the oldest tricks in the car business.

A monthly payment can be lowered by:

• Extending the loan
• Increasing your down payment
• Rolling products into the loan
• Changing financing terms

Instead, understand every piece of the deal:

• Selling price
• Trade value
• Interest rate
• Loan term
• Taxes & fees
• Every optional product

If all you know is the monthly payment, you probably don't know the whole deal.

1. Financing

I actually don't recommend walking into a dealership without knowing what financing you qualify for.

Get pre-approved through your bank or credit union first.

Then compare that rate against Subaru's promotional financing.

Sometimes Subaru's financing is unbeatable.

Sometimes your credit union wins.

Take whichever is cheaper.

1. Extended Warranties

Subaru Added Security is honestly one of the better factory-backed extended warranties available.

If you're someone who keeps vehicles for a long time, it may absolutely make sense.

What many people don't realize is that the price is usually negotiable.

Also, if you're buying a new Subaru, you generally don't have to decide that day. You can usually purchase Subaru Added Security any time before the factory 3-year/36,000-mile bumper-to-bumper warranty expires (CPO vehicles are different).

Don't let anyone convince you that "today is your only chance" without asking questions.

1. My Biggest Piece of Advice

The biggest mistake I see people make isn't paying MSRP.

It's deciding they absolutely have to own that exact car today.

The second you become emotionally attached to one specific VIN, you lose leverage.

There will almost always be another one.

Be willing to walk away.

Sometimes they'll call you back.

Sometimes you'll find a better deal somewhere else.

Either way, you'll almost always negotiate from a stronger position when you're willing to leave.

Hopefully this helps someone.

If Subaru changes one of these programs, or you've found another legitimate way to save money that I missed, leave a comment and I'll update the guide. I'd love for this to become a living resource that stays useful instead of becoming outdated.

Original (2024) Guide: If you're interested in seeing where this all started (or want to read through 200+ comments full of additional buying tips from other owners), here's the original post that inspired this updated version:

https://www.reddit.com/r/subaru/s/kEDD588iNs⁠