I used that foil backed adhesive foam in some areas on my van. Its lightweight, it does cut down the road noise a bit. But recently I put in a layer of butyl rubber dynamat type stuff and the difference in noise reduction is massive. The stuff weighs a lot, around 3kg/m² for a sheet less than 2mm thick. Seems weight is king. Apparently if you run a foam layer then an isolated heavy layer it cuts sound even more effectively. I've just got the dynamat layer straight onto the metal to stop it vibrating/transmitting the sound. Might put a foam foil layer over it mainly for heat insulation.
This was done on the front doors BTW. Its really worthwhile doing those doors, huge difference in road noise.