There is a company I have been thinking about using, JET-HOT, that does a
ceremic/metallic coating, I think both inside and outside.  Try http://
www/jet-hot.com/about.htm                I have not used, nor can I recommend,
but I am thinking about having the manifolds on my MG TF done.  Hope this helps.
Larry

Ken Hunter wrote:

> Don't think powder coating will hold up to the temps. There are high temp
> coatings for exhaust that would extend the life and preserve the appearance;
> check the hot rod magazines for the latest. Have had personal experience with
> aluminizing which, although susceptible to scratching, held up well and
> seemed to lower head temps. Some of the other coatings may actually insulate
> and raise head temps which may or may not be what you want. Wrapping the
> exhaust with insulating asbestos or whatever they use now to increase exhaust
> temps for turbo applications greatly reduces the life of the exhaust pipe
> (but really helps performance). Robert Lilly who built some improvements into
> his WBX engine highly recommended some internal coatings but I don't recall
> if he did the exhaust. Maybe he will respond.
>
> Ken Hunter
> 82 Westy 1.9D
> 84 Jetta w/motor out
> 89 Mitsubishi van
> 79 Rabbit 1.5D (donor)