I just bought a used 2007 mini cooper s with 83000 miles. I notice that when the car is warmed up and I am driving around 2000 rpm, a large rattle occurs towards the front right. it has an alta cat back on it. For the most part when I let off it goes away or quiets down. I looked underneath the car tapped on the exhaust with a rubber mallet and the only thing that makes noise is the flex pipe, but it is the stainless mesh that is woven over top of it. I tapped around for something loose and am finding nothing. Check engine light is not on. any suggestions?

 

Check the metal shields around the front of the exhaust near the down-pipe. Sometimes people remove the nuts to move the shield around when installing a down pipe exhaust.

They don't tighten them back and they can rattle at certain vibrations.

#5 in the front


http://www.ecstuning.com/Search/18307595606/





#19 for the back


http://www.ecstuning.com/Search/11657588556/



Then check the exhaust set up and make sure something in the exhaust is not touching them and rattling.


Also check the top heat insulation near the turbo ( when cool of course ). It can rattle if not bolted down.
#17 in the second pic.


http://www.ecstuning.com/Search/11657595605/

Thanks and hope that helps.