Will powder coating hold up to the heat of a head pipe.
I am not a metalurgist but at Delphi where I retired we heat treaded our powercoating to extremly high temps and baked it for 1 hr to seal and bond the powder. I am not sure what the header pipes get but it might be ever hotter at the top..
The rule of thumb on powder coating exhaust is; anywhere the chrome "blues" is too hot for powder coat. If you just want the heat shields, and most mufflers, done you won't have a problem.