Depends if your going to recoat it or not natural finish strip it and aluminum brghtener then a neutralizing wash, might want to clear coat after words, this will give you a clean as cast look. Recoating grabs some toilet bowl cleaner scrub it with an abrasive, neutralise wash and what ever color you like. I like vht cast coat aluminum or iron if you want a darker grey, but there not a match for stock, stock also has a bunch of factory paint marks if that's the look your going for.