Here's some advice on Mustang horns. When Andrews Powder Coating does car horns, there are no guarantees due to the excessive heat involved. Heat can damage the horn's internals, rendering it inoperative. If they are instructed to do it anyway, they seal the horns for media blasting. Some components, such as idler arms, tie-rod ends, and the like with bushings, seals, and bearings, cannot be powdercoated due to risk of heat damage.