Quote:
Originally Posted by bullmrkt
If it has the vacuum valve (like virtually every other BMW does for sound regulations and cat warmup) just unplug the vacuum hose and stick a screw or golf tee in it. Then the butterfly valve will stay open all the time for a bit more sound and deeper tone.  |
That's exactly my question. Does the M3 have the valve to open up all 4 exhausts? Or are they open ALL the time?