The results are quite good for an application that can be done in less than an hour with a cold engine.
Before Calyx
The only drawback with Calyx is that it does not last very long. It can be touched up, of course, but it requires constant care and maintenance.
Again Calyx exhaust manifold dressing has to be applied when the motor is cold. And after you're done, it's a good idea to start it up—outdoors if you did the application in your garage—and allow the motor to get to operating temperature.
You will see some smoke emanating from the manifolds and you will smell the stuff, but that only lasts for a short while.
Once caveat; after a few weeks, DO NOT wipe the manifolds (when they are cold, of course) with a rag, as the finish will rub off easily. At that point, the only solution is the apply more manifold dressing.
There are other alternatives, including removing the manifolds from the engine, cleaning and spraying them with VHT (Very High Temperature) exhaust and header paint, but that takes more work, you'll need new gaskets, etc. I do not know how long a VHT paint finish lasts though.
But now that the engine of my car is out for a rebuild, the chance to get the exhaust manifolds done professionally presented itself, and I decided to have them ceramic coated.
But factory exhaust manifolds are cast parts and do not look good, in my opinion, with a shiny finish. It actually cheapens the look, so for that reason, I've stayed away from having that finish applied to mine.
However, after talking to a few people in the ceramic and powder coating industry, there are other finish options available for headers and parts exposed to high temperatures.
In addition to the aforementioned chrome-lookalike finish, you can have them coated flat or satin black or with a gray/cast finish.
I looked at a couple of samples at Performance Kote in Orlando, Florida, the shop that did mine, and even though the "cast" finish did not look 100% correct, it was close to what a freshly cast part looks like, and a lot better than the shiny or black alternative.
So I went with that choice and I am very pleased with the results. For around $240 and about a week's time, they are now durable and they should maintain that clean, rust-free look for quite a while.
After Cast Ceramic Coating
If you decide to go this route, know that ceramic coating will not smooth out pitted metal or eliminate the porosity of the finish, especially if the manifold had severe rust spots. A good shop will prep the part to the best of their ability, and many dip exhaust manifolds in an acid bath that helps remove baked-on grease and carbon deposits, plus a thorough bead blasting will help considerably to improve the look of the surface.
Just like with paint, preparation of the surface that is to be painted—or in this case ceramic coated—is 90% of the job, and it pays off in the end.
I also bought a new set of replacement studs for the manifolds, and they will be installed by the shop when they are ready to reinstall the rebuilt motor, and I also purchased new grade 8 nuts, bolts, and washers, plus French bolt locks for that factory-fresh look.
Of course, it will be interesting to see how this finish "wears" once the car is back together and I start putting miles on the freshly-rebuilt motor, so I will report as to how the cast ceramic coating looks after the exhaust manifolds reach operating temperature.
UPDATE: 2/2/2020
This is a recent photo of the right side of the engine which shows the condition of RHS exhaust manifold about 3½ years after the ceramic coating was applied. Both sides look new, so ceramic-coating was definitely the right choice.
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