Not sure if powder coat will be long lived before it starts to change colour Fatbat, ceramic coating the lot my be the safest bet, and the colour on all the parts will be perfectly matched.
Painted heat shields years ago using supercheap VHT exhaust paint. Gave the chrome a scrub up with 400 grit wet rub until it was all dull. Painted my FLHS muffler the same way. Now and then the muffler gets scratched so I give it a quick spray and it is as good as new.