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      03-14-2011, 01:54 PM   #26
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Drives: Krooked Sk8board
Join Date: Feb 2008
Location: Pasadena, Ca

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hey guys i wanna talk bout exhaust and gains for the N55.

As some of you may know i've been prep'n to dyno
Injen's intake and in doing so I found some interesting finds in my
exhaust + oem intake from my recent pulls.

To fill you in, this is the process I've taken in the past week or so.
-received new injen intake - test driven no dyno.
-then removed intake, took e90 to dealer for 15k service (scheduled service)
-E90 was reprogrammed according to mandatory update.
-drove a few days with stock intake, for adaption to settle with bimmer
-Dyno'd with vanguard exhaust and stock intake.
-removed stock intake, installed injen intake -
-been driving around a few days with injen intake, letting the adaption feature settle before dyno.

I got the numbers for the dyno with the exhaust + OEM intake.
and look'n at these numbers compared to my baseline numbers
it show some loss in power.

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I lost a few whp, torque number seems to be fine but pass 5800k
you'll see the drop up top. There were no gains.

Looking at these numbers lead me to think -
that the oem exhaust really does not have a restriction.
Unlike the N54 or the N55 xi where you'll have cats the only
restriction the n55 does have are the double cats on the DP.

does the N55 xi have 1 or 2 cats on the DP?

Honestly the exhaust adds great sound but i see no gains.
anyone else do a dyno with their aftermarket exhaust?
if the findings are similar, I would make the conclusion
that gett'n the Catless DP before an exhaust would make more
sense. I have DP's and the procede next up to bat for my N55.
I like to see if any gains would come out of DP's and a after market
exhaust for our N55.

let's discuss.
E90s (been gone but not forgotten) KW clubsports 18" BBS GT4 // Build E30 (pending) + E46 M3 Wagon ESTORIL Blue