Ive just managed to pick myself up a rear M3 bumper with diffuser (99p from a popular auction site!!!) and will need to be preparing and painting it to match my car. Is there a guide on the best way to go about this? Ive repaired the wheel arches etc before but have never worked with plastic bumpers. Im asuming that there is differences in the prep and possibly the primers and paints to use. Any help/advice will be greatly appreciated. thanks.