I would like to add some clarification on powder coating and ceramic coating, both for general use and high temperature applications.
First: powder coating materials and techniques have not developed a high temperature finish. Powder coating has a high temperature range of 600F to about 1000F with emphasis at the lower figure. In other words, powder coating should not be considered for exhaust manifolds (at this time).
Second: ceramic coating has a maximum temperature of about 1600F which will go well with exhaust applications. I saw some samples on smooth pipe and the gray was very close to what a cast iron manifold should look like, although there were no samples of cast iron available.
After consulting with Jeff, I was encouraged to enter a disclaimer, powder coating and ceramic coating were not processes used in the automotive industry when most of our cars were made. They would not be accepted in formal MCA judging.
On the other hand, on cars I've restored to the daily driver level, I've had several parts powder coated: bumper brackets; the front engine cross member; rear axle housing; mostly under body items that get a lot of road wear and tear. Brake backing plates and front springs could also be added to the list.
For more information about powder coating and ceramic coating, refer to the Processes section of this forum and feel free to contact them.
Jim