Easy Fix:
Take the license plate off, and remove the black plastic piece. Mine had marks from where the screws for the license plate were tightened town all the way and scratched away at the paint. Seal the original holes with silicon, and drill into the scratch marks from the license plate holes. The original holes wont fit the US plates (further apart)... Put a thin strip of foam all the way around where the license plate is going to cover slightly smaller in size than the actual plate. I used a dry erase marker to make an outline of the plate after mounting it in the new screw holes. I also put a small bolt through the holes and a small nut on the back side of the door (had to take off the plastic trim piece). You rarely have to change your license plate, so its not too much of a hassel to take that panel off to access the bolts. I also took the rear wing off and put foam around that (theres a how-to here on that). The rear door has ZERO rattleing right now. Even with the sub up all the way. No more ugly plastic piece, and no more rattle.
