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TurboKraft TurboKraft is offline
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Join Date: Mar 2005
Location: Phoenix, AZ
Posts: 2,656
wastegate muffler pipe

Yes, that muffler tip for the 1986-89 Turbos. It's a piece of junk on a non-stock engine because it is so restrictive. We have seen it cause between 2-5psi (!) of boost creep on modified 930 engines.

Internally, it is a moderately perforated tube with approx. 68x 5mm holes, and the end of the tube folded/pinched in a square pattern, leaving the WG exhaust to flow through the holes plus a 3x3mm center opening.

Our local track is 94db or 96db. Routing the WG outlet back into the muffler inlet isn't difficult and, when the engine has a big 3" straight-through muffler, allows the car to pass.
Ex: exhaust on beyond-GT2-spec 3.8TT

FWIW: testing a 3" dump pipe vs. one of those big 3" mufflers, we measured a 2whp difference -- within the normal variance of back-to-back dyno pulls on a Turbo. Hardly any loss.
Chris Carroll
TurboKraft, Inc.
Tel. 480.969.0911
email: -
Old 05-20-2013, 01:43 PM
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