Exhaust Coatings---I have a mechanic that does muscle cars in Mountain View. His name is John at Diamond Ridge Motorsports (650)964-4040. John did mine and I was out of town so I don't know who he had them done by. My second thought is to ask a header/exhaust builder.
This company is in South San Fran
http://www.sandersonheaders.com/index.php
This company is in the Sacremento area
http://www.spdexhaust.com/index.html
And this guy is in southern Cal, Costa Mesa.
http://www.burnsstainless.com/index.htm