I decided to try polishing my plastics rather than buying new so i went for it today.
i started with red automotive scotch brite pad to get the big stuff out
then wet sanded with 600 grit, 800, 1000, 1200, 1500, 2000, and then polished with 3m rubbing compound, and 3m finesse it 2 finishing material.
They came out pretty well, they are nice and white, but not perfect.
My only complaint is that wherever there was a sticker would not get any better, those spots are still very dull, even where my ORV sticker was for only 8 months, not sure why this is, but i'm satisfied and will run the plastics like this for awhile.
here's some pics, they dont really capture the sheen very well but it's there