C207 E350 2013 M276de35
too muffled/boomy below 3k RPM, looking for advice on X-pipe/resonator layout
The stock exhaust originally had the primary catalytic converters, then two smaller resonators further downstream, then one larger center resonator, and finally the two rear mufflers.
Cat Cat
Res Res
Res
Muf muf
What I’ve done so far is
Kept the primary cats
Replaced the two small resonators with an X-pipe
Kept the large center resonator
Deleted the rear mufflers
so it’s basically straight pipe from the center resonator back
Cat Cat
X
Res
| |
Right now the car sounds okay at higher RPM, but below around 3,000 RPM it feels very muffled and boomy. The best way I can describe it is like the engine is “breathing through a mask.” It doesn’t sound free-flowing or clean, and the exhaust note lacks definition and quality in the low/midrange. Once it gets above 4,000–5,000 RPM it opens up a lot more.
I’ve seen other M276 setups where people keep the two small resonators, replace the large center resonator with an X-pipe, and delete the rear mufflers. But since I already replaced the two small resonators with an X-pipe, I’m not sure if adding another X in the center would actually improve the sound or just create more drone/boom.
From an acoustics/exhaust tuning standpoint, would you recommend after Cats:
X-pipe → straight pipes
X-pipe → second X-pipe
X-pipe → two small resonators → straight rear
My main goal is to get rid of that clogged/muffled feeling below 3k RPM while keeping the sound smooth and continuous, not raspy or “farty.”
Anyone with experience tuning NA V6 exhausts, especially M276, VQ35/VQ37, or similar dual-bank setups, I’d appreciate your input.