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      12-17-2012, 07:16 PM   #17
roadkillrob
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Drives: 08 335i,22 X3M, 2012 C63 Black
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It has nothing at all to do with emissions or it could not be legally disabled - PE exhaust would need to say for off road use only if disabling the flap messed up emissions and a non functional flapper would need to set the check engine light if it was part of the emissions requirements.

It is purely to pass the noise tests at certain RPM's that sound levels are measured at, then can open to allow more flow and better sound at higher RPM's.

Torque - no difference, that is controller by how quick boost is built and how high boost pressure is, that is controlled by the wastegates.
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