I've had good luck with the spray bomb method...Used VHT the first year I put my car together, without any heat processing and the paint flaked right off (And stunk too)..Second time around I wire wheeled the headers until they were bare metal, heated em up till they were glowing hot with a torch (you can feel the heat coming out the opposite side) and while they were hot, sprayed about 2-3 coats of the paint on. That finish lasted perfectly fine, required no breaking in with heat on initial firing of the engine, and is cheap and looks good too