Jet Hot
I had Jet-Hot coat my new Spitfire Headers a month or two ago. As far as dealing with them (i.e, phone call, shipping, return shipping, price, etc.), it was a good experience.
The coating looks really good, but I can't address it's durability - or longevity. In fact, the headers are still sitting on my workbench, cause the weather here (in Kentucky) has been too blasted cold to work in the garage lately.
But I would advise you to call Jet-Hot to make arrangements. I got a 10% discount on the coating by doing so.