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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
Per the article referenced above on Turbo Exhaust Theory, a 3" pipe's limit is about 400hp. That migh be with a front to back exhaust system where gasses cool, slow down, and create back pressure so I am not sure about us with our short exhaust path.

However, he also notes a taper just out of the turbine to I believe aid in flow and inhibit turbulence.

With many passing the 400fwhp range on our 930's, a 3.25 or 3.5" system may have some measurable benefit.

I really like what 125 shiftr did here to perfectly match his flange to the turbo and immediately transition to his chosen tube size.

My old B&B was not anywhere as well fit and had more of a step out of the turbo. Most of the builders seem to cheat this area.

Originally Posted by 125shifter View Post
The exhaust flange was water cut to match the turbo housing, then the flange ID was taper machined to perfectly match the K27HF2's 2-3/8" outlet to the 2.5 to 3.5 tapered pipe. A short piece of 3.5" elbow is welded to the tapered pipe to point it to passenger side:

Old 03-08-2009, 08:10 AM
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