All header manufacturers I am aware of you will void the warranty using header wrap. Yes, it traps moisture and destroys them faster.
The problem with ANY of the paint out there, is that it does not coat the INSIDE of the header. People may be missing that, (its in the quote above) but 50* underhood temp and 300* header temp (less) are not insignificant numbers. You can't do that with paint, and you can't do that with an exterior only coating. I saw it with my own eyes on the Hedmans that had some overspray coating inside the runners, night and day difference when I was breaking in the engine. (which you are not supposed to do BTW)
The problem with ANY of the paint out there, is that it does not coat the INSIDE of the header. People may be missing that, (its in the quote above) but 50* underhood temp and 300* header temp (less) are not insignificant numbers. You can't do that with paint, and you can't do that with an exterior only coating. I saw it with my own eyes on the Hedmans that had some overspray coating inside the runners, night and day difference when I was breaking in the engine. (which you are not supposed to do BTW)
to heat them up good and bake the paint on.
