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Old 04-30-2012, 09:24 PM
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Yorgi Yorgi is offline
Officially Welcomed to the 'Fest
Location: Toronto
Join Date: Mar 2005
Posts: 3,650
Mein Auto: '04 M3 / '06 650i Cab
Originally Posted by leon920802 View Post
Why s everyone using x pipe instead of straight?
Benefits of an x-pipe:
1) reduces rasp
2) slightly quieter exhaust than straight pipe (noise cancellation)
3) equalizes pressures on each bank of cylinders
4) the biggie: causes a plunging/scavenging effect.

The scavenging results from the initial "pulse" of gases coming down one header then hitting the X joint. Now the gases have two pipes to travel down. This increases the speed of the gases. At the same time the other header will now experience lower pressure which causes the plunging effect (like a vacuum) and this sucks out the gases when the other bank of cylinders fire. This makes a big difference at higher RPMs.

Moving the x-pipe to the rear is better for power but installing up near the headers sounds better. I went for the better sound option.
Straight lines are for fast cars...turns are for fast drivers
'04 M3 - track
'06 650i Cab - daily driver
'02 Highlander - kid hauler
'01 330Ci - winter beater

Last edited by Yorgi; 04-30-2012 at 09:25 PM.
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