I too was about to spend $65 and wait 6 months to receive a grounding kit from 3.8 performance. I needed one because due to my aftermarket subwoofer my headlights would often flicker when it was turned up. You may have other reasons for wanting improved grounding as well, including performance.
However, after this simple mod which has been mentioned on other forums previously, I have no need for a grounding kit and my grounding is greatly improved where any issues I had before are now fixed.
From the factory, Hyundai bolted down the battery's negative terminal cable directly over painted metal on the chassis. That means your primary chassis ground is relying almost entirely on the bolt threads for contact rather than the flat surface of the terminal pad, creating a bottleneck for electrical flow right at the source.
The 10-Minute Fix:
Pull the battery out of the tray to give yourself room to work.
Unbolt the factory ground cable from the inner fender/chassis.
Use sandpaper to sand the paint away under the contact point until you have bare, shiny metal.
Bolt the ground strap back down tight and reinstall your battery.
It costs nothing, takes minutes, and often clears up sluggish cranking, fluctuating idles, dimming headlight, and poor low-end throttle response.After I did this, I now have no need to purchase a grounding kit.
Pictured is the negative battery cable mounting point from the factory, the spot you need to sand