I had some leftover roofing matt material I'm applying to the floors & rear vertical. I've sprayed my fuel tank cover sheet metal in rockerguard and will be stuffing some Roxul under that cover and in the tunnel voids on either side of the tank. I completely coated my rear wheel wells with Herculiner on one side and rocker guard on the other (for rust proofing) so sound deadening should be a side effect of that.

I heard of people using the foil/bubble wrap product as well - has anyone here tried that?

Hardtop makes a huge difference on long highway drives and stereo noise is much better with it on. I also dyna matted the rear shelf and did not notice too much of a difference in noise reduction.