I think somebody's been blowin' smoke up your butt. You are correct that JetHot is a header coating. If the piece that is being coated is prepared properly there will be no moisture under the coating. There are two or three exhaust coaters that I would trust to do it right: HPC, JetHot and Cap's in Fresno, Ca. Powdercoating is very durable and it would have to be hit a ton to chip it. I recently bottomed out my frame on a speed bump and it was roughed up a bit but the scratches did not go through to the metal. That's all you can ask. None of these coatings are bulletproof, but then, what is?