I've hadn't noticed before since i am always inside the car, but my brother pointed it out to me the other day when he passed by. But there is a distinct rattle that is coming from the exterior rear passenger side of the car. it is sounding like it is coming from inside the fender but it also sounds like it is coming from underneath the car. I initially suspected the muffler heat shield, but the noise is not a can-like rattle, more like a plastic-rubber type of rattle. i posted in this forum because the noise is only coming out when i have my stereo turned on. Just wondering if anybody else has come across a problem like this. I really should blame my dual 12" L7s, since i've got them i'm finding new rattles every day.

 

Actually now that I'm taking a better listen at it, it sounds like a flapping sound from the rear of the fender. kind of like flicking a fly swatter on the edge of a table repeatedly. hmmm... might have to remove all the panels in the back area to take a better look.