The ceramic coating will help keep the underhood temps cooler..atleast on headers it does.

I had a set of 340 manifolds done in a high temp powder coat that my local powder coater uses. They look great and they claim it holds up on manifolds...headers not so much due to them being thinner and getting hotter.

I wanted this done for looks mainly. Cast iron manifolds w/o anything on them look like crap after a while. This should last a long time and look good. I've never been happy w/ any of the spray can type of manifold treatment.