Do a search on this forum and also search Google for how to insulate small aircraft. Those techniques are very informative and effective.

Adhesive butyl products like Dynamat Extreme and Fat mat are good at stopping panel resignation, which is good. The real secret to keeping noise and heat out of the cabin is to use a double foil sided padding to cocoon the entire interior. Be sure to seal all the seams with that foil ducting tape with the wax paper.