dumb question there is a valve on one of my exhaust tip..what does this mean? does it mean that it only works at a certain speed?

yes, one of the tips does have a valve which opens at higher rpm's//gears. It's basically for noise reduction. There's a way to actually keep that valve open all the time though: https://5series.net/forums/topic/844...ost__p__993989

thanks alot for the clarification

Interesting. I went ahead and tried to see how the actuator works, and I see that by default, the spring loaded mechanism in it keeps it closed. On the E9X series cars, it seems that the flap mechanism works the opposite way, in that vacuum in the line keeps the flap CLOSED. So by simply unplugging the tube, the vacuum pressure is gone, and the flap remains open. But in this car, it seems to work the opposite way...

Unplugging the tube didn't do anything, as it seems the tube uses vacuum to OPEN the flap under WOT or higher RPM's...

So I played with it while the car was idling just to see (by using my hand to open and close the exhaust flap) and it sure made a difference in noise!

So then I figured I'll see how I can leave the flap open all the time, to get a deeper exhaust note during regular driving. I ziptied the arm that keeps the flap open, and went for a drive.

Unfortunately, I could barely hear a difference in the cabin, probably because the cabin is so well insulated, but even with the windows down, I couldn't hear much more, unlike in the E9X series, where it makes a big difference.

Bummer!

http://www.youtube.com/watch?v=6LSVm4BjiVU

Doing the golf tee mod or unplugging/pinching the hose can void your warranty if they catch you doing it so do it with some disgression.

Thx for the heads up, but I think they'd have a real hard time doing that and blaming it on causing what to fail? Not sure if you've come across people that's happened to, but on the E9X series 335, the BMW Performance Exhaust that is sold has no actuator in it, and the tube is just pushed onto a pin on the exhaust so it doesn't hang down. So BMW themselves in a way have acknowledged by designing their own exhaust that way (which doesn't void your warranty of course) that the use (or lack thereof) of the actuator has no impact on the turbos, engine, downpipes, catalytic converters, etc.

interesting, my brother has a 335is, so the e9x performance exhaust comes standard, at cold start up the exhaust produces an annoying ringing/rattling sound. It goes away quickly, once warmed up. But fr0m the threads I've read that ringing was due to that valve and to perform the golf tee mod to remedy it. :think: The other suggestion as to what is causing the ringing is the wastegates...hmmmm