I'm with bowlcut and brian here. The stuff is too heavy. I had it in my last car and while it did work, it weighed a ton. For my SE-R, it opted to go to hardware store and buy undercarriage sealant. Spray it on, let it dry, and while it won't do as much as as Dynamat, I now have $198 dollars more to put toward performance. Hey, that's a throttle-body, shaved flywheel or half a clutch.
Racing is all about compromise, though. You want more top end, mess with your timing, but you'll lose bottom end. You want good fuel economy, don't mash the gas off every stoplight just cause ther's a Honda next to you. And if you want a quiet car, be prepared to pay a hefty price in the wallet and your e.t.! If the quiet is worth it to you, I applaude your purchase.
General observation: I don't like some guys (primarily Honduhh owners) who want everything. "Man I want a 12 sec. daily driver with two 15 inchers in the back and a playstation," they say. What ever happened to people understanding that sports cars are not luxury cars. Your car SHOULD be loud if you want 12, 13, or 14 sec e.t.'s. Granted you don't have to strip the interior, or sacrifice a sound system, but keep in mind what your ultimate goal is, whether it be performance, sound system, comfort, showcar or whatever. Personally, I'm performance oriented, but since I drive 100 miles a day for work, I want a good sound system too. Everyone is different.
Just an opinion,
ryan