Well, you initially stated it as a fact, but it seems to be an opinion. I'm just trying to provide a distinction between the two.
Thermal coatings are allowed on headers and exhausts, because the GCR specifically says those are unrestricted.
Thermal or anti-friction or thermal barrier or impregnated or anti-gravity coatings are specifically considered non-compliant when used on internal engine surfaces and the insides of intake manifolds. The GCR states this clearly. Why call out a list of specific parts where those coatings cannot be used, but not include other parts ? "You can't paint your front porch green" doesn't mean that I can't paint my back porch green.
It's known that many stock calipers come painted. It's not known why they're painted. Is it for corrosion protection, or for heat transfer, or for both, as rust is a lousy conductor of heat ? We don't know, so it's difficult to make the argument that using a good heat radiation paint or coating 'performs a prohibited function', which some might cite as a counter-argument. It's not a 'tortured' interpretation, in that light.
The real test is "What would the SOM's think, and then on appeal, what would a Nat'l Court think ?". Until someone can cite an example of a Nat'l Court finding, this is all just opinion.
I probably have more 'appearances before the SOM' than you have 'race starts' (not sure whether that's good or bad...). My opinion is that I could convince an SOM Court that it's legal. I have no idea as to how it would fare at the appeal level, if it got there.
But it's an interesting question.
