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      03-01-2011, 04:42 AM   #1
cwidjojo
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performance exhaust (eisenmann) decrease power?

so i went to a pretty well reputated tuning company in the east coast last weekend to look around and ask about my future mods, and particularly, i asked how much power an eisenmann race would produce on my car.
the owner said it in fact is going to decrease power due to lowered backpressure compared to the stock system. is this true? seems hard to believe, because isn't the second most sought after effect of an aftermarket exhaust the power? (after sound obviously)

nonetheless, he said a tune would fix it and bump (he assumes) 40hp overall. he provides cobb tuning.
what do you guys think?
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      03-01-2011, 05:10 AM   #2
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There are few dynos on the forum with Eisenmann Race installed on M3s. Some have reported an increase of 6-9whp whereas few vendors say 15whp. Either way, none have shown a lost in power.

They just mufflers after all.
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      03-01-2011, 05:13 AM   #3
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Don't ever set foot into that so called reputable shop ever again.

Reducing backpressure won't decrease power, period. Sometimes it can affect low end torque by shifting the torque peak to the right a bit but it won't reduce peak power.

To answer your question on how much power to expect, the answer is very little, expect 1-3 HP max from an axle back exhaust. Power gains from exhausts on the M3 (and most cars for that matter) are made by removing the cats or adding highflow cats. Axle back exhausts are for sound and not performance.

If you want a nice sound put on a muffler. If you want a performance gain add an x-pipe with high flow cats or even better, no cats at all.
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      03-01-2011, 08:29 AM   #4
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That guy is seriously uninformed! Like the above people said small gains but no losses...
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      03-01-2011, 09:03 AM   #5
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Quote:
Originally Posted by BMRLVR View Post
Don't ever set foot into that so called reputable shop ever again.

Reducing backpressure won't decrease power, period. Sometimes it can affect low end torque by shifting the torque peak to the right a bit but it won't reduce peak power.

To answer your question on how much power to expect, the answer is very little, expect 1-3 HP max from an axle back exhaust. Power gains from exhausts on the M3 (and most cars for that matter) are made by removing the cats or adding highflow cats. Axle back exhausts are for sound and not performance.

If you want a nice sound put on a muffler. If you want a performance gain add an x-pipe with high flow cats or even better, no cats at all.
Damn Strait +1

That guy's just another [sic] tuner who learned the business from magazine articles.
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      03-01-2011, 10:05 AM   #6
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Quote:
Originally Posted by BMRLVR View Post
Don't ever set foot into that so called reputable shop ever again.

Reducing backpressure won't decrease power, period. Sometimes it can affect low end torque by shifting the torque peak to the right a bit but it won't reduce peak power.

To answer your question on how much power to expect, the answer is very little, expect 1-3 HP max from an axle back exhaust. Power gains from exhausts on the M3 (and most cars for that matter) are made by removing the cats or adding highflow cats. Axle back exhausts are for sound and not performance.

If you want a nice sound put on a muffler. If you want a performance gain add an x-pipe with high flow cats or even better, no cats at all.
+1

BMW i imagine is banking on people buying this system so they can have a differnt more aggressive sounding note without having to void their warranty.
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      03-01-2011, 05:27 PM   #7
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Cobb can't tune an M3 anyway, so run far far away from this guy
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      03-01-2011, 07:23 PM   #8
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If there was a rear section + tune that could produce 40RWHP we would all have it. This guy is 100% wrong on everything. Full catless exhausts from reputable companies like Dinan and Akrapovic only claim 25HP with a tune. Check Dinan's site for their "white paper" article on backpressure. It's a good read.
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      03-03-2011, 03:31 AM   #9
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thanks for the responses guys - i appreciate it. seems like he might have been misinformed about NA engines. he tunes a lot of GTR's, evo's, and such... a lot of japanese performance cars, so that might have influenced his perception.
anyway, a member here got his exhaust installed by them as well, and it looks like a very clean install!
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      09-18-2012, 03:18 AM   #10
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Quote:
Originally Posted by cwidjojo View Post
thanks for the responses guys - i appreciate it. seems like he might have been misinformed about NA engines. he tunes a lot of GTR's, evo's, and such... a lot of japanese performance cars, so that might have influenced his perception.
anyway, a member here got his exhaust installed by them as well, and it looks like a very clean install!
free flow exhaust helps on turbos even more in my opinion. I think he is just uninformed in general.
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