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RarlyL8 RarlyL8 is offline
Crotchety Old Bastard
 
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Join Date: Jan 2000
Location: Huntsville, AL
Posts: 13,423
Garage
Primary and secondary ID are critical to velocity. I use 1.5" primaries and 2" secondaries up to 450WHP and 1.625"/2.25" beyond that. You also have to take a look at the rest of the build and see how/where the power is made to size the headers appropriately.

The stock Euro system is thick walled and I have not cut one of these in two to check the ID. The early Euro/USA system has very tiny secondary pipes.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 01-16-2010, 04:20 PM
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