The better heading coatings available will help cool the manifold, but it needs to be coated inside and out. But wait, now you also need to coat the exhaust pipe because all the heat from the exhaust will now radiate out though the pipe. Header wrap will also keep heat heat in, but you will need a couple of manifolds due to the heat cracking and warping of the extra hot manifold. Headers do the same thing if when street driven. A simple air duct will do more for cooling the alternator then the coatings would.
