Ceramic Coats

Have a look at websites,

http://compcoat.com.au/coatings.html

http://compcoat.com/

Same place...

Although I have not had work done here, my neighbour uses these guys for his Race Car exhausts.

There are other places that do Ceramic coatings too.

For your exhaust, less heat transfer, more horsepower, non-corrosive non-rusting finish.
The Ceramic coats inside and outside the pipe.

Looks great too.