I used some DEI gold wrap on my intake. I am happy with how well it seems to work, I sure wouldn't do it just for looks.
After my turbo install my header the coupler to the intake on the kit was shorter so it brought the turbo side of my intake down a couple inches and with the header being much taller than the manifold, at one point only being 1 inch or less from the top of the header. Since I had the header coating and it would take a couple days to get some parts to correct in I decide to drive to work and back the next two days as is just to see (15 miles each day).
I kept a close eye on it and I guess the coating does do its job, it started to shine the plastic on the cobb intake but didn't really start to melt it through, but it wouldn't have lasted very long I am sure. But I figure still impressive not melting plastic a finger width away from the top of a turbo header even for daily driving.
So I got a 2 inch spacer built to bring the intake back up to the normal location and wrapped the intake and then went out and did a half dozen data log pulls, and then I checked the temp under the header section of the intake and the wrap was almost unnoticeably warm to the touch. (note it was not raining on the intake during the pulls, that picture was after it set out in the rain overnight with the cowl off)
Anyway it's hard to get good info on how much coatings and wraps really help, and that is my experience.