I hear MOTHERS BACK TO BLACK is the product to use, from the paint and body guy. But I hear that it wears off fairly quick so repeated applications are necessary. Now I'm going to tell you what I did. Go on YouTube and search for HEAT GUN ON PLASTIC. Trust me, it worked for me. My panels were pretty faded and it brought them back to like new condition and it's a hell of a lot cheaper than new panels. Watch several of the videos and take your time doing it. Just a suggestion.
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If your stupid today, it's a safe bet you'll be stupid tommorrow!