Straight pipes on my 87 325is

[denisbmwm5]

My whole exhaust is starting to comedown. the converter is rusty and the pipes by the rear control arm are squeeshed half way. I got a dtm dual inlet muffler that i just got and put on there and ill probably use it in the new exhaust. My question is how big of piping to use, and should i use a converter or not? Here in Florida we dont have emmesion tests anymore so no cat would be no problem. Do m20b25 sound good with straight pipes?

[Rob]

there is no reason to run without a cat on the street. None whatsoever. Modern cats are higher flowing and less expensive than ever. But a universal cat from www.jegs.com or www.summitracing.com

Your car will get really loud without a cat btw

[denisbmwm5]

Yeah i know its gonna be way louder cuz i got straight pipes on my 98 328 and it sounds good, just wanna know if it sounds good on e30s.

[denisbmwm5]

The reason i want to run straights is performence wise.

[Mystikal]

Do it. If it's too loud, throw a resonator in.

[nando]

The reason i want to run straights is performence wise.

it's not going to make your car any faster...

[Rob]

not by much at least, although the placebo effect and more noise will make you think otherwise

[rwh11385]

I know e9nine had straight on his former car.....not sure if he posted ckips, but I had the feeling it sounded 'dirty'. It might be loud, but probably will sound like SHIT.

I need to replace my cat sometime, but either high flow cat.....or would a resonator in its place work too?

[Axxe]

I drove my car for a day without the rear exhaust section, and I got a noise ticket ($40 CAD). Other than that it sounded wicked. At low rpm's it burbles like a race car, and at 6k rpm's it's way too loud. Can't listen to radio or anything, and I had a huge headache after an hour of driving.

[Rob]

I know e9nine had straight on his former car.....not sure if he posted ckips, but I had the feeling it sounded 'dirty'. It might be loud, but probably will sound like SHIT.

Well I bought his car and drove it for 8 hours, got a good idea of the exhaust sound. I liked it, with the stock muffler it wasnt too loud. Cant comment for the power changes


I do know a local guy added straight pipes to his built 2.8 stroker, got really loud, sounded good, and he says it pulls hard. but he has a balls out built motor

[denisbmwm5]

Yea i was thiking or using some sort of a high flow cat or resanator. what exactly is a rasanator? its build like a cat? or muffler? im asking jsut i never experimented on them

[Rob]

Cat:

http://auto.howstuffworks.com/catalytic-converter.htm

Basically scrubs the exhaust gasses. has the side effect of quieting the exhaust noise.

A resonator is basically a smal hig flowing muffler, usually tube shaped, whose purpose is to reduce noise.

[Ball325]

when rebuilding my car we started it with just exhuast manifold. IT SOUNDS ORGASMIC! it would sound like a true race car with just a straight pipe. Put if you put a cat back on it it might just sound raspy like something is broken, you either need to build an exhuast thats likely to be over 90dB or run a normal street exhuast.

[kylebes1]

I just had pipes back to a Magna FLow muffler and it was WAY too loud, well I thoguht I wouldhave a hogh flow put on to make it quiter, it did nothing and I could fell thetop end get weaker.

[Ryan Stewart]

Hopefully mine wont be too bad. I have S52 headers and downpipes to a AA 3" collector back to a 3" Borla stainless muffler. And I am actually taking this from advice from a few S52 boys and the price was right....

Free! 8)