gutting the cat

[Smatt90IS]

i have a 90 325is with a supersprint exhaust cat back and i want to gut the cat this weekend since we dont have to pass emissions in NC i was wondering if it will make it sound like shit since i have a freeflow muffler

[lennon]

dont gut it, please! if you think something will be gained by not having that "restriction", just cut it out and weld in pipe in its place. of course keep the flange so you can just bolt it up to the cat-back still. honestly, why are you trying to gut it? if nots not clogged and causing problems, just keep it. you wont gain anything except maybe some smoke.

[Asbradley21]

It will be very loud, put a resonator in it's place, it won't sound much different.

[lennon]

i do disagree with that ^ though. my m20 car has 2.5" single pipe from headers back to a magnaflow muffler and its not loud. different ideas of loud though.

[Asbradley21]

Well, my m42 car was single 2.25" all the way back to a tiny ass magnaflow (really short, about the size of a phone book) and it was loud as shit and raspy as hell. Tossed in a resonator, sounds much better, deep and throaty.

[iX-treame]

Not that it matters because its a small loss, but you do loose back-pressure.

[Smatt90IS]

what kind of resonator should i use?

[xwill112x]

just weld a pipe up in place of it. i dont even think m20's are capable of being raspy.

[Aptyp]

^that's because you have an m42. This is turning into NC discussion. Go to autozone and get a thrush cherry bomb to use as a resonator.

[SpecM]

^Go to autozone.

no, go to Advance

[nando]

if your cat isn't clogged, you have absolutely nothing to gain by gutting in it. more than likely you will lose performance because you're going to kill exhaust velocity once it hits that big, empty chamber and the exhaust gasses expand and cool.