i was reading up on Silica Aerogel and its thermal protection properties. supposedly a very thin layer of it can absorb enough heat that you can put a 1000 degree F torch underneath it and the top part will be cool to the touch.
anway, even with an aluminum heat shield over it, an exhaust mani still puts out a lot of heat into the engine bay. i'm going to make a thin nomex "bean bag" filled with aerogel crystals to see how much it lowers engine temperatures.
i'll update the thread as the "bean bag" starts to come together.