Just got done sanding down my rear bumper after taking off a haze that developed as a result of some stuff I put on it last year to try an restore the black finish. The bumper was in pretty good shape, no deep scratches or anything, so it only took a few passes with some 200 grit sand paper to get rid of the haze. I'd like to restore it to the deep black finish it would've had when new and have read where you can get good results with sanding and polishing. My question is, what kind of polish/rubbing compound would be good to use? I've seen some folks mention 3M, but is there a certain one that would work best? The last thing I want to do is use something that's going to cause some kind of damage to the urethane.