Wow, that IS a clean finish! I went with a carpet and found some real thick dense padding at a carpet place, NOT the standard lightweight foam stuff they use for indoor carpets. And I had a lot of noise coming through, now it's like i'm in a sound booth, of course, new weather-stripping helps too. In fact I also used it as a under hood insulation and works great. Most of the catalogs sell sound deadning stuff.
Vile, does that stuff also work like "chassis coat" rust prevention, i thought I saw a can in one of your pics.