Taming Down My GMMG Setup

[Brady21x]

I'll have to crawl under her tonight and see what sized sweet thunder will fit for a length wise in the I pipe

[Injuneer]

The Borla XR-1 race mufflers work well. I had a 3" XR-1 on each collector, then a 4" Mufflex catback system with the Flowmaster 30-Series 4" single in/4" single out muffler. It was fairly mild sounding, but would start to throb under any sort of heavy throttle. The XR-1's are straight-through mufflers and about the best you can get for minimal power loss. The oval one will provide the least loss of ground clearance. The 3" and 4" ovals are only 4.25" high.

[Brady21x]

How much would an XR-1 tame the drone and rasp you get vs say a moroso spiral flow?

[Brady21x]

Or would a High Flow Cat be a better option?

[Injuneer]

My original setup described above had the ability to run either 3" CarSound high flow cats on the collectors, or the 3" XR-1's in their place (track use, C16 leaded fuel on nitrous). To me, the XR-1 plus Flowmaster sounded quieter than the cat plus Flowmaster. I have no idea what a Moroso spiral flow would sound like.

Right now, the 4" Mufflex catback is gone, and I have 3" pipes back to the axle, with turndowns. The sound is still decent, but not ridiculously loud with just the XR-1's. The turndowns are actually turned inwards to try and keep the sound under the car, because the local track has a noise limit of 90dB @ 100-ft, under full power. Was close on that one, until they changed the rule to state that not only did there have to be a muffler, but the muffler had to have 3 chambers.