I did my entire car in BrownBread (doubled in some areas), and then did a layer of their L-Comp, which is a much heavier weighted sound reducer, all along my tranny tunnel and in the hatch area. It made a slight difference, but it didn't reduce the transmission/exhaust noise as I had hoped. It did dramatically reduce panel rattling, and the stereo was much nicer sounding, so that was good. However I ended up spending over $500 for it, plus it added ~100pounds to the car. If its a daily driver, itll help a little, but its not going to turn your Camaro into a Lexus or anything. I may just go back and pull out the LComp, since that is where most of the weight is coming from, and then just leave the brown bread. Also remember a lot of the noise you hear when driving is wind noise, so this isnt going to alleviate that at all. But on the plus side I found a few bucks in change from pulling all the carpet out!