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      11-04-2011, 11:43 AM   #64
pbonsalb
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Drives: 08 E90 M3, 99 E36 M3 Turbo
Join Date: Feb 2011
Location: Concord, NH

iTrader: (3)

It looks like Vishnu gained 13 rwhp and 28 lbs rwtq from welding straight pipes in place of the cats on a stock midpipe, with no tune.

http://www.m3post.com/forums/showthread.php?t=585325

I am sure there are some dynos around of "name brand" catless midpipes, with no tune. I would think that nice mandrel bending and maybe a better X section would be worth a few rhwp, though I am not sure how perfect the X needs to be in order to have the desired balancing and/or scavenging effect.