well i used an adhesion promoter, then the color coat, and that was it. Duplicolor does offer a bumper coating, which basically is flexible color with adhesion promoter built in. SEM makes something similar; SEM Bumper Coating. I've also tested both of these (i painted the gray plastic on my rear bumper step, and the front gray lower valance plastic) and the SEM held up better. I only used a clearcoat on my colormatched pieces, which are all rigid plastics.
im not saying that duplicolor sucks... far from it. like i said earlier, all my colormatched pieces were painted with an adhesion promoter, then duplicolor colormatched spray, then duplicolor clearcoat. However, imo from actually TESTING different brands was that SEM holds up better than others to normal wear/tear/scuffs/scrapes/etc.
, SEM doesnt do colormatching, however they have way more colors in their flexible color coat line than duplicolor, so you could probably find one thats very very close.