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      03-15-2018, 07:23 PM   #18
SeanWRT
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Drives: E90 M3 & F87 M2
Join Date: Sep 2015
Location: Shanghai

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Heard a while back that you guys are making a catted downpipe as a stock replacement. Is that still in the work? Is there an option of going 3.5" outlet to fit your catback system? Do you use HJS core, most importantly for a catted system.

I like the idea of increasing diameter a little bit for more power. Few months back we actually tested how N55 catback pipes diameter effect power at 450whp+. Bigger diameter definitely helps.

At the rear end where one pipe split into two, rather than two 3.5", actually two smaller pipes (still bigger combined than single pipe upstream) are preferred, as exhaust flow gets cooler and shrinks as it travel thru pipe so less cross section is needed to maintain velocity, though smaller pipe makes less decibels. What's more is this system bends radically, twice, right before muffler while most competitions bend only once. Two bends hurt flow, which may or may not make a difference.
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