when I got my new "pimpy" header for my ITA Integra I first ordered it with no coating - they wanted like $150 to do it. I ran I think two events on it with no coating before deciding to send it out. I got it coated inside and out and I think it did wonders. The under hood temps really did decrease. Also, my header just dumps into a 2.5" exhaust with a Thrush tube to "take the edge off". If you know, the Thrush comes painted red and usually that red painting will stay pretty well kept. However, after I had my header coated, the paint on the Thrush started baking, turning black, chipping off, etc. You can definately tell that the heats being taken through the exhaust and not into the engine bay.

I'd never do the header wrap bacuase it just accelerates the breakdown of the metal. The wrap only wraps the outside of the header so the heat still gets into the metal but has no where to go - that greatly reduces the life of your header. The ceramic is inside and out so you don't get this problem.