I feel your pain with all this. I'm running over 3000 watts in my G3. The reason you hear rattles with the windows down is because, well, simply put the windows in our cars mechanically kind of suck. The whole mechanism is really loose and stuff, and I don't know if there's anything we can do about it or not. Literally, the window itself is rattling against stuff inside your doors. If you find a way to fix this, let us know!