I have a 2002 330CI that i have had for a year now. For the last six month i have had a rattling noise that is coming from the back of the car, next to the rear window. I took the car to BMW dealer in Dallas, and they said that they can't do anything because the car has an after market stereo. They say that the radio is making the car rattle. Does someone have any advise. The noise is killing me.