I did the whole sound deadening removal -> hate it -> replace it fiasco years ago. I agree that the firewall stuff was the most important, as the carpet and backing effectively takes care of the floors. Don't use dynamat on the firewall, though. Use thicker felt padding like this Thermo-Tec 14130 - Thermo-Tec Thermo-Guard FR Heat Shields - Overview - SummitRacing.com. It worked well in my experience. Mass loading (like dynamat, et al) doesn't work as well on the frequencies that you're trying to cut down on.