[randywebb]

"the stock type pad only slows the migration of heat into the cabin versus the foil type that reflects the heat back into the engine."

- Here is what is happening: You have to consider the different modes of heat exchange. The surface of the foil reflects almost all the heat that radiates onto it right back onto the engine. The surface of the stock (dark) pad will absorb virtually all the heat radiated onto it. So it is about 100% vs. 0% for radiation. Heat will also be transferred by convection, but that will probably be much less. The pads may or may not differ much in how they are convectively coupled.