their website tells the tale, if you look at the faq section they address how to "fix" the coating "if it flakes or fails to adhere"...
they try to cover their arse because of the high failure rate, and even go so far as having "liability" statements printed there also to get out of litigation, when it fails inside someones mega buck painted harley tank....heheheh
Yeah, you had to do the preparation very carefully and then do the same with the application. I never had problems, but I know many who did. That would play havoc with a newer type fuel pump and injection system.
Oh wait... you said Harley...