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      03-16-2007, 02:43 PM   #33
SteveMD
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Drives: '12 X5 50i, '15 GTI w/PP, LP
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This is the 'Golf Tee Mod'. It has nothing to do with back pressure or performance. It has to do with noise and specifically low frequency reverberation at low revs. Something that non-enthusiasts may frown upon being a luxury car etc.

The valve is closed at low RPMs to keep noise in the cabin down. At higher RPMs (not sure when and can't be bothered to find all the other threads that have discussed this) it opens up the second zorst.

It does not slow the car down.
Removal of pipe does not throw any codes.

Removal of the pipe will keep the flap open since the failsafe mode is open.

IMO, the car sounds louder on idle and low revs.
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2006 E90 330i (retired)
2009 E90 335i (retired)
2012 E70 X5 50i M Sport, JB Stage 1, 4.6 secs 0-60.
2015 VW GTI LP PP