Exhaust piping diameter?

[ColdAccord]

for a 2.7i. i think I'm gonna do the 325i/is dual exhaust. i had planned on just doing a single, but I think I'm going to sell my brullen muffler, and just get the dual custom made

just wondering what diameter I should get the piping. obv i'm already gonna have low end, and will already be having trouble with traction

[65Matt]

single 3" should work.

[Mystikal]

I'd say dual 2.25". Stock is just under 2" (45mm).

[Beej '86 325es]

Sorry to steal the thread, but does anyone know what diameter the pipes on an E36 3.0 M3 is?

[Stu]

Single 2.25 or 2.5 will be plenty. 3" will be drone-city on a small displacement motor like that. Dual 2.25 will also be excessive.

[rwh11385]

Guys, didn't you get the memo? Bigger is always better. :P Be like Dan Pinder. 4" = pimpness.
Joke stolen from Rob

On a serious note.... If I ever get an exhaust, it would be single 2.5". And single would probably cost a less than custom dual. Just get shorty headers, y-pipe after that, and run it to a muffler like Jamie's

[ColdAccord]

single is supposed to be more low end, dual for high end

my shit is a 2.7 stroker. so i'd imagine it will have sufficient low end torque. so i'd imagine i'll be having trouble with traction

therefore, i inquired about this

[Stu]

single is supposed to be more low end, dual for high end

my shit is a 2.7 stroker. so i'd imagine it will have sufficient low end torque. so i'd imagine i'll be having trouble with traction

therefore, i inquired about this

You won't have trouble with traction. I run a 275/265 S50 in my 318, with high treadwear 205's, and traction is not a huge issue.

Exhaust tuning depends on much more important factors (like, the engine), as opposed to number of pipes.

[E30godz]

a single 2.25 has less flow than the dualstock piping. ask me how i know. add the cross sectional area of two 1 and 7/8ths, you find that it is more than a single 2.25.


for the NA motor, the 2.5 single is choice.