Chuck at Bonehead performance, [email protected] quoted me $160 for a pair of Dll exh manifolds. That is plus shipping and I think quite reasonable.
My sons Dll is down waiting for rebuilt long block so I think I will have them done.
For the very marginal gains (in heat reduction), I'd spend the 160.00 somewhere else. Any gains in horsepower would be miniscule. Remember, you have the blazing hot cats still essentially under the hood. Also, there are very different qualities of "ceramic" coatings. If you were talking a full length header in a high hp vehicle, then getting the heat out starts to be advantageous. When I had mine out, I just bead blasted them, hit them with high temp manifold paint, and they're still looking good after a couple of years.
I used to sell ceramic coated manifolds. They were a little bit more expensive that the price you were quoted but that could be because of where I am or because of the way they were done. I don't know.
These days, I sell used manifolds that have been bead blasted and I recommend buyers use a quality hi temp paint like helievacpilot said above. I never get requests for ceramic coating these days.
The price is good but make sure they do a thorough job in coating. I've seen some pretty crappy examples over the years.