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Discussion Starter #1
Guys, I know there are a lot of threads on different exhaust setups that lose power from decreased back flow pressure...

With my current setup, E-race with SS X-pipes (no resonators), I do notice/hear some free flow through the exhaust (occasional faint popping noise at idle)...I don't really feel a power loss, but haven't dyno'd the car as of yet...

Question is...will software fix this? I'm contemplating RPI pulley and ESS software as my next mods...hoping this may improve the air flow?
 

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i have the rpi pulley, as well as ss stage 2 software...still get the popping
 

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Discussion Starter #3
i have the rpi pulley, as well as ss stage 2 software...still get the popping
so the popping IS loss of back pressure?...do you have loss of power?
 

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i think i may be losing a little bit of power...i had the x-pipe on and i think i was losing a good deal of power with that...i switched to the high-flow resonator instead and it seems to have improved..i havent dynoed the car since then to know for sure, but it feels a bit better...check and see if when u shift, u get a pop/air sound...that is lack of back pressure if you do, from what ive been told.
 

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if you talk to a bmw service person, they may also have a tool that measures the back pressure of the car, so that you can know for sure whether it is in the area that it should be or not
 

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Discussion Starter #6
what did you replace Sxn 2 with...Evosport? what is your current setup?
 

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Was going to have mine done next month. Maybe I'll wait and see what happens to yours.
 

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so the popping IS loss of back pressure?...do you have loss of power?
Popping sound occur when there is a sudden change of air flow. It occurs is a free flow exhaust system, which means minimal backpressure. :)
 
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Hey guys, ive been wondering about this issue for a while now, cause kelleners didnt touch my stock resonated rear section and i think its for that same reason of the X-pipe showing negative results. So im craving to know the diffrence between the (resonated SS X-pipe) and the stock resonated rear section.. do u think theres any add of hp and sound between these 2 ???? a dyno test from one of you guys who installed X-pipes will solve the problem :biggrinbounce:
 

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Discussion Starter #10
With my setup, basically, the SS X-pipes deepened the sound and made it louder. As far as hp, haven't dyno'd, but I can guarantee I have no gains in power with the SS X-pipes....Sxn. 2 is mainly for sound.
My other issue is increased free flow (loss of back pressure), and I was looking for suggestions on how to fix this...
 

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I also get that popping sometimes during downshifts. But never under acceleration. I certainly dont feel a loss of HP, if anything it feels stronger. And compared to your setup, my exhaust system should be higher flowing.
I havent heard of anyone losing HP from the E-Race muffler or from the SS X-pipes.
 
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