exhaust

[M20bmw318i]

what is the best cat back performance exhaust system you can get on the market. it doesnt have to be the loudest, just the most hp gain. and does anybody have a dyno sheet to show any exhaust gains.

[M20bmw318i]

for an M20b25 motor
sorry

[A_325i]

for an m20 you wont gain much if any hp the stock exhuast is ideal ...you are pretty much going to gain sound and looks a catback system(good quality will run you a decent penny your better off getting a custom exhuast made just buy the piping the cat and the muffler and it shouldnt cost you anymore then 350 to install it thats what i did and i couldnt be happier

[M20bmw318i]

exhuast

i have an M20 runnning 10.5:1 compession and a 290/290 cam. i have the headers from bavauto. with no cat. i was just seeing if they made a good exhuast for me. Were did you get those 19lb injectors from and do they have anything a little bigger

[Jordan]

19lbs is more then enough for whatever m20 build you have.

[M20bmw318i]

is there any other bmws i can take injectors out of. like any of the newer M3 that would do the same

[A_325i]

i think the m50 engines injectors will work

[M20bmw318i]

b/c i have also heard that injectors out of the 5.0 mustang work good too. i think im going to get the tri-flow exhuast, i want something that is load but sounds good.

[nando]

more than 19# injectors without custom tuning would be a very bad idea, you'll drown your motor in fuel (ECU adjustments are limited in their range). M50, S50 and 5.0 mustang all work fine though.

[A_325i]

i have the mustang injectors in my m20 and they work perfect 8) i bought six of them for 40 bucks in mint condition on ebay

[M20bmw318i]

would the best thing to do is get the unichip piggy back? is there one better than that like the smt6? i want something that i can tune a good amount of things

[joshh]

for an m20 you wont gain much if any hp the stock exhuast is ideal ...you are pretty much going to gain sound and looks a catback system(good quality will run you a decent penny your better off getting a custom exhuast made just buy the piping the cat and the muffler and it shouldnt cost you anymore then 350 to install it thats what i did and i couldnt be happier

I don't believe this statement is true. Any time you allow the motor to "breath" better, your going to see some power.
The stock exhaust is deffinately not "ideal" if you want any more power than stock. As soon as you start adding even bolt ons you'll regret sticking to the stock exhaust. Then again anything you do to the motor should be a master plan and not added piece by piece unless it's part of the master plan.

[Budget Beater]

17lb M50 injectors would be much better option than 19lb mustang ones. Also the statement that exhaust does not make HP is completely false. people here are R3V are running DUAL 2.5" pipes thinking this is going to make power not realizing they have no clue on anything about exhaust systems. Too many guys are running improperly designed exhaust systems and are losing power as a result of it and then saying "no power to be made". Not true. a properly designed exhaust system WILL make power but there really aren't any out there with the exception of the long tube headers and a properly designed custom system. the rest of the way back.

[M20bmw318i]

i am running a set of headers from bav auto with no cat and ansa cat back system, but i wanted to get more sound out of it. so i was thinking of putting the tri- flow system on it. i kno bmw's need back pressure but you also need to let it breathe, i am almost running 11:1 cr in my motor.

[Budget Beater]

its a very delicate balance of back pressure and free flowing charactersitics. but runing huge diameter multiple piping is NOT the answer. mathematically-wise one 2.5 or two 2.0" pipes all the way back are optimal .