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      03-25-2015, 01:27 PM   #56
chris82
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Drives: 128i
Join Date: Aug 2012
Location: NY NY

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2009 BMW 128i  [9.80]
Quote:
Originally Posted by TheAxiom View Post
Judging by 613's numbers, It probably will lose power.
Quote:
Originally Posted by TheAxiom View Post
It's either a. the Intake (which I think attributed to part of it, or b. The exhaust system - the transition between the stock exhaust and the new muffler,or even the muffler itself could impeed flow and cause a loss in power.
No way. The pipes on the 135i muffler go straight through, no restrictions at all. The diameter is slightly larger too. I think it was the Injen or like you said, the connection of the 135i exhaust to the rest of the system.

Here is what's inside the 135i exhaust, thanks to whoever took the time to do that: http://home.comcast.net/~david.johns...MWMuffler.html

According to his measurements (David Johnson?):

"The full flow pipe is ~2.4" diameter, for 4.2 square inches.
The valved pipe is ~2.3" diameter, for 3.8 square inches.

4.2 + 3.8 = ~ 8 square inches through the resonator, and out the tips.
5.7 in, 8 out. Not much of a restriction, except maybe the "S" bends."

Last edited by chris82; 03-25-2015 at 01:34 PM..
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