If I was racing, I would want the thinnest coat of flat black that will protect the metal. Powder coat and thick, luscious paint look great. But coatings can hold the heat in, especially on finned aluminum parts that are supposed to air cool. That also applies to brass or aluminum radiators. Now if you are just looking good with monster brakes, and have very few panic stops in a row, please disregard the rest of this post and go blue or red and neatly painted lettering.