Opines or facts please

I have two heat insulators to choose from to try on my car. One is from Holley, a 1/2" item made of layers of gooped paper. The second is a resin impregnated/phenolic looking piece.

The Holley piece is compressible as evidenced by the hard plastic bits used in the mounting holes. The resin piece is hard...not compressible at all.

Anyone with experience with either/both of these? Is one a given better insulator over the other?

This isn't a great big deal. I'm just curious if there is a plethora of opinion one way or the other.

Thanks.