Eventually, the vacuum-operated exhaust valve in BMWs with sport exhausts will go bad. They start to rattle at startup, and then later they cause nasty, loud, flatulent sounds at 3000+ RPM --- just imagine a cross between a whoopy cushion and glass-pack mufflers...this is not a great sound. The official fix is to have the entire valve replaced. But, since that is expensive and welded into the muffler, it's often not worth it. The exhaust in my 335i is still in great shape, so there is no point in replacing it just yet, either. If your exhaust valve is still in good condition but you want to annoy the neighbors a bit more, this makes the exhaust a bit louder below 3000 rpms. They probably already hate you anyway.

This is a variation of the Golf Tee Fix, which involves disconnecting the vacuum hose which goes to the exhaust valve and plugging it with a golf tee. You then shove the offending hose somewhere out of the way. I'm not a golfer, and I refuse to buy a bag of tees for this application. Also, there really isn't a good place to shove the vacuum hose once it's plugged. And finally...a golf tee....really?

This object solves all of those problems. You plug the vacuum hose onto the post on one side of the part. You then slide the part over the hose nipple on the vacuum valve and zip tie it into place. The hose has the exact same routing as before, and it's pretty easy to remove if you ever need to make a trip to the dealership.