Just 1100 grit wet sand and Menzerna FG400 compound on a rotary buffer, seen in pics. You can use any compound and follow up polish to get same results. The key is to remove enough with the sandpaper. If you don't remove all of the clear coat from the plastic then it'll yellow again or stay yellow. Just need to follow up with a UV resistant coating like wax or sealant...Or a new clear-coat.