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      03-21-2009, 09:13 AM   #35
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J08M3's Avatar

Drives: 2011 M3 COUPE
Join Date: May 2008
Location: NEW YORK

iTrader: (8)

Originally Posted by dogears View Post
Actually the primary cats are one of the biggest exhaust restrictions. By switching to a higher flow spiral core cat, such as emitec, there is a 8-10 peak hp improvement with more than that gained in the midrange. The trick is finding one that doesn't code.
Agreed they are the biggest restriction. Problem is having a cat in the first place. I could definitely see 8-10 hp by eliminating cat all together. Not sure if there's a good HFC out there that will give me 8-10? I don't want to mess with my ECU and have to worry about sending it out to some tuner.