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      07-24-2010, 09:29 PM   #9
Diokaef
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Drives: M235I 2015, 335i 2011
Join Date: Dec 2009
Location: TAMPA FL

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2008 Z4M Coupe  [6.33]
Yes, but the only good results came from exhaust with diameter under 2 1/2" for 6 cylinder. so the pressure inside the pipe is higher and speed is possible do to higher temperatures and higher pressure inside exhaust.

All the gains that I had opportunity to observe was a full exhaust including mufflers and no cats.

with Headers only I had not observed any improvement and also no much gains with the ones with straight pipes (no Mufflers).

and in my opinion after see the results (Bad results) a very bad idea if you have ceramic cats and or cats with more then 200 CEL what usually caused the exhaust to fail miserably.

A good gain would come from Headers, middle section, and x-pipes with mufflers.

The mufflers only will be done with exterior coating.

I don't have any copy of the results as I was only able to observe them live.
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