Muffler rattling noise when shifting and at idle 03 mini cooper

I have a manual 03 mini cooper S, in the benining i noticed a vibration or rattling kinda noise when i went trough 2000 revolutions +/- but not when im going less or more than those revolutions, like if the noise came from underneath , a rattling noise, and today i noticed that when idle in neutral i could hear something rattling underneath the car , so i checked and it seemed like the muffler was shaking or something. what could this be and how can i fix it? i really appreciate your help guys.

also when im going fast at 5th or 6th gear the rattling noise does not come anymore. it just does it when im crossing the 2000 revolution mark and around.

i have not experienced any loss of power or anything funny in the car, its just that rattling shaking noise :S help

While it is possible that an exhaust component is loose, it is more likely that you simply have a loose heat shield. When the car is put on a lift, it can be checked for both conditions.

A loose heat shield is annoying, but not dangerous. However, a loose exhaust pipe can lead to CO poisoning, so this should definitely be checked out.

thanks for your reply, i will try to take my car tomorrow for a check up, mini coopers are so small its hard to check under by my self :P, i need a ramp. i hope its just a loose muffler shield