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Old 02-01-2001, 10:07 AM   #1
Scooby Guru
Member#: 1725
Join Date: Jun 2000
Chapter/Region: International
Location: Germany
99 Subaru Impreza
GF silver

Post Noticed strange "valve" on BMW exhaust tips. What is it?

I was driving behind this newer 3 series and noticed that on its dual tip exhaust that one of the tips had this valve or flap that would open and shut, leaving one of the tips open and on certain occasions, the other shut. What is up with that? It was cool to watch it open and close. Just wondering if this is some active exhaust back pressure thing?
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Arnie is offline   Reply With Quote
Old 02-01-2001, 10:59 AM   #2
Scooby Specialist
Member#: 2003
Join Date: Aug 2000
Location: Calgary, Alberta, Canada
'99 BGP Legacy GT
'98 QS Legacy L (auto)


Yup, IIRC the new Maxima & I30's have the same thing... as well,the new Outback w/ the H6 has the variable chamber volume mufflers... suppose to provide better response @ lower rpms.
GTBGUY is offline   Reply With Quote
Old 02-01-2001, 07:21 PM   #3
Scooby Newbie
Member#: 305
Join Date: Sep 1999
Location: PA, USA

its actually been on 2.5/2.8 litre bimmers since 1997 or 98. basically it allows for more backpressure at lower revs and/or throttle position and hence quicker torque delivery.

m3s never had it though.

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Old 02-01-2001, 09:00 PM   #4
Scooby Newbie
Member#: 502
Join Date: Nov 1999
Location: Sydney, New South Wales, Australia

In the US it is claimed that the flap increases bottom-end torque, which is the kind of thing the American market appreciates.

In Germany, it is claimed that the flap makes the car quiet at low speeds, which is the kind of thing the German market appreciates.

Andy_T is offline   Reply With Quote
Old 02-02-2001, 12:52 AM   #5
Scooby Newbie
Member#: 2878
Join Date: Nov 2000
Location: Nuevo Mexico, usa
06 Evo IX MR


Yamaha motorcycles had it in the early 80's, their name for it is EXUP, they still have it...
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