I just asked my dad who has run em for years, he hasnt found ANYTHING that will take it off unless its a stripper, Im sure there is something , try a baking soda concoction, Im just not sure brake cleaner will get off the baked on ****. To be honest, look at motorcycle shops and hot rod shops, alot of them use coated headers that change color and they have chemicals to rectify that, they might have something for ceramic coats. Rubbing compound might be worth a shot since they arent installed yet. I know turtle wax brand is really abrasive, might work.
Sorry if I wasnt any help just trying to think back 10 years.
