[MasterAnubis]

I wouldn't use butytl on the inside of the hood. Heaven forbid that turns out to be asphalt.

The underhood insulation is not just for heat but for sound. With the heat under the hood (unless the manufacturer says) I wouldn't use just adhesive to secure that anyway. Manufacturers use mechanical fasteners. They may use adhesive as part of it but they use flanges and the pins with large washers for the most part.

I have seen Ford go with and without underhood insulation depending on the trim levels of a car.