Painting headers?

The high temp stuff from POR doesn't go on over rust like the POR15 rust paint. The metal needs to be rust free.

I used POR20 which is the aluminum colored coating and it is by far the best high temp coating I have used, it lasted for 3 years and 20k miles before starting to break down . Much much better than VHT.

The headers I coated were very rusty. I used Muriatic acid (fireplace cleaner) to dissolve the rust. Three applications with about 5 minutes wait and all the rust was gone. If you do this do it outside because the reaction gives off some strong fumes and do it in a place the dog or cat won't get at it.