To me, Dynamat is extremely vital if you want to install a sound system, especially one with strong subs. For my gen4.5 it dampened nearly 90% of the vibration and rattling I had before. You get better SPL and tighter bass. Trust me, you don't want to spend thousands of dollars on a great sound system only to turn up the volume and hearing nothing but annoying rattling sounds. I put Dynamat Extreme on my trunk lid, trunk floor and wall, rear deck, and a little bit in the front doors. The trunk is especially important since the sub is back there and that's where most of the rattling comes from. Oh yea, remember to put it in back of your license plate too since that's the first thing that rattles. I bought the bulk kit and it included 9 sheets of Dynamat. I think it's the best kit for the price, rather than buying the door kit and trunk kit separately. If you don't want to use Dynamat then there's also Hushmat, Fatmat, Scosche Accumat, and Stinger Roadkill. I used Dynamat because they are the original sound dampening material and I think they are the best, just my opinion.
