That's what I was looking to objectively figure out...where the point of diminishing returns is. I've read beau-coup postings about how sound deadener works or doesn't work. There is so much back and forth about it that I believe that once someone has installed it, a placebo effect kicks in. (similar to the "go-faster" effect that makes all kids with new gym shoes run 15% faster )

I've ordered 75 sq ft of Dynamat Extreme as a start. Rob S suggested in a previous post that the firewall is the best place to begin. Dynamic Control reports big noise reduction by doing the doors. Anything has got to be better than it currently is. You actually have to raise your voice in the car to be heard over the noise from the road, engine, mufflers, etc.