Him Jeff here; Sorry to hear about your noisy Cooper. If you don't feel any problems while driving such as running rough or handling funny, you probably have a loose muffler. Any muffler shop or service station can have a look at the underside of the vehicle once it's raised on a lift, and many don't charge for this. Always be sure about any charges for a visual inspection, and be careful as most repair orders' fine print authorize work based upon your signature, and unscrupulous shops will add work to the R.O after it's been signed. Some won't charge you if you allow them to do the repairs, so call a few local shops. I don't know what the status of your warranty is, but it never hurts to call a dealer to find out if your problem is covered-you can do this before or after a shop inspects the vehicle. If the exhaust system is loose then as it moves around other parts of the system will eventually suffer damage-this can only add $ to the repair bill. Please have someone check your vehicle as soon as possible. Ask your friends, neighbors and/or co-workers if they have a shop they truly trust as honest, and please let me know what the problem was. I await your reply, Jeff.