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Old 10-07-2012, 04:31 PM
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Join Date: Aug 2009
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Mein Auto: 2009 E93 N54
Originally Posted by Elk View Post
Only if during the time the flap is normally closed, the engine is being held back by the failure of sufficient air to move through the exhaust. This is not the case.

Even a full exhaust replacement makes relatively little difference in HP and torque on this engine, perhaps 3%. Accordingly, a tiny mod which effects only part of the exhaust in during a limited RPM range is doing nothing.

Besides, if power was this easy to generate and the only downside is a slightly louder engine, don't you think someone at BMW would have thought of this? It takes a untrained, backyard mechanic to figure this out?

The perceived change is purely emotional - "it's a tad louder and I made a change. Therefore there must be more power."

Expectation bias is vastly more powerful than this exhaust mod.

There's a boost, smoothness & torque, beyond doubt - it's movement off-idle I'm talking about.

Power is that easy to generate all other things being equal. Yup, it was shadetree guys who tried & liked it. Popular thought's that noise regs created the flap, tho emission volume [not %] may have played a part.

Hey, try it. If you no like, easy enough t'return to stock. Looking for map specific settings so's can snip the wire tie....

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