E30 Exhaust Disappointment

[e30strokr]

get the ebay exhaust manifolds thinner metal amplifies the rasp sound..

[roguetoaster]

OP, just stick a potato in your exhaust.

[varg]

Rasp and "hollow" typically go hand in hand, just listen to a new edge mustang with flowmasters. Hokey explanations about pulse order and such you'll find on forums aside, if you look at an actual spectrogram of different exhaust sounds, rasp is identifiable as excess of higher frequency noise relative to the lower fundamental frequency noise that is the frequency of exhaust pulses. Funny that you're looking for the rasp, most people try to eliminate it. Since the M20 doesn't rev high enough to be a screamer where the more pleasant high frequency noises dominate the rasp, mid range rasp typically is not viewed as pleasant. Straight through mufflers and narrower pipes (i.e. stock size pipe and mufflers) will tend to let the rasp through without the "hollow" mid/low frequency resonance that you typically get from big and/or thin pipes. Cats are great for eliminating resonance since they're basically a resonator with a flow control device (the matrix) inside them. So choose a bolt on system based on clips, or weld a resonator in.

[onesecond]

Go on on a few websites, see what they offer and then look them up on youtube. There are tons of videos with their exhaust notes recorded

[Stanley Rockafella]

https://www.holley.com/brands/flowma...ies_big_block/
This'll get it flowing freely and give you that stock sound (not empty/hollow) yet quiet.
Also a dual in, dual out, so it'll weld up exactly where the old cat/resonator was - similar dimensions too.

[6th Element]

I have an ‘89 325i with the stock M20 and a Turner Chip.
my exhaust system has been stock with the exception of a Borla Muffler for quite some time now. I had been contemplating changing the exhaust note a bit. I was hoping to acquire a more raspy sound. So today I had an exhaust shop replace the cats with straight pipes and to my disappointment, it sounds god awful. Sort of like a 325 E46 with a muffler delete
it has a very “empty/hollow” sound. I’m not sure if it’s because I have stock manifolds or not.

My question for you guys is, what makes the M20 sound raspy? Would an X pipe change the tone as opposed to just straight pipes? Maybe even some eBay long tube headers?
I’m aware that exhaust modifications won’t gain any power on a stock M20, maybe even lose some low end power, but in all honestly, this car’s my weekend toy and occasional canyon carver.
thank you guys in advance!