it actuates a flap when the car turns on that blocks off one of the tail pipes....if you look in the pipe you will be able to see itOriginally posted by Import2ner@Sep 2 2003, 05:43 PM
Is there much sounds difference after you do this modification. Me and a friend were going to try it on his car one night, but wanted to see how it would affect the car first. One more question.....Do you know what the vacuum valve actually does?
if that does indeed control the flapper valve in the exhaust, i assume the "more exhaust sound" is because the valve is continually open. the valve is an exup valve, and the reason why bmw put it in is because they could run bigger headers without sacrificing low rpm torque (vavle=closed at low rpm).Originally posted by the mod
This is another one of those little changes that does little to nothing. It basically adds a little more exhaust sound in the lower RPMs at light throttle.