i just had a 3 inch straight pipe welded and installed on my x. it revs somewhat smooth up to 6800rpm but my bottom end is non existant . I do notice that it pulls harder between 4-6ooo. theres a burschur airfilter as well(it sounds cool but i dont feel it make power). Is this performance expected with a straight pipe and no ecu tune? btw im new here and thanx for haveing me !

 

with straight pipes you has less back pressure, so down low you will lose some power but you will gain that up top

 

how does less backpressure cause loss of power down low? The exhaust wheel of the turbo spins faster and spools quicker. please explain this to me

 

So let me get this straight you just got a 3" straight pipe from the cat all the way back with no muffler. If that is true had does that sound, I can see it sounding good at all. If you just got it done the computer still maybe adjusting. I know when I put on my cone filter I reset the ecu and it seemed to help alot.

 

backpressure gives you low end torque I believe. I had a cbr 929 that had a valve in the exhaust system that would open above a certain rpm, this came stock and it was i was told to leave it on and just put a slipon.

 

i believe this is true of N/A motors only. With turbo cars, the less piping connected to the exhaust side of the turbo is better... someone please correct me if i'm wrong.

 

yes its 3 inch from the cat back (mandrel bent tubes) No muffler at all. Its sounds like a evo now and its not that loud. No ecu problems yet or dash lightscoming on. does anyone know what type of performance i should expect from a ecu tune with this mod?

 

Wow if you get a chance i would love to hear what that sounds like. Can you post up a sound clip if you have time. I bet that was a pretty cheap mod at the local muffler shop. I tried to get a custom exhaust, but no one in san antonio has a mandrel pipe bending machine.

 

did u reset the ecu ? how long have u driven it? could take a 100 miles or so to learn them.

 

soundclips would be nice

 

what company is your test pipe from? j/w

 

back pressure is actually kinda bad for the turbo, I agree, more flow out from the turbo is better.

 

you would think it would be loud but it sounds like a 9 with a turbo back exhaust system. but it does sound badass !! now that I have the factory reflash i do feel more power on the topend . as far as price ,it was cheap( $315 otd) and installed .

 

who reset the ecu for you? i have seen on some threads people talking about reseting the ecu. are you referring to unpluging your battery?

 

I think i remember reading about this before. Back pressure does not increase torque but rather exhaust escape velocity. I would agree with evox_sa in that you should probably try resetting your ecu. That might help.