I think people have gone off the deep end using Dynamat, Brown Bread, and the other sound deadening products. Some people spend hundreds of dollars doing their entire trunk, roof, doors, floors, etc. and I recall recently reading one post where there really wasn't much of a difference afterwards. Vibration dampening products do work well but have you ever knocked on the floor in the trunk of a Maxima? It feels about an inch thick and rounded sheet metal at fenders, wheel wells, etc. is also stiff and solid. These areas are not very likely to vibrate noticeably in the subwoofer range. Dampening the trunk lid, rear deck, roof, doors makes sense since the metal does flex in these areas but the floor, fenders, and wheel wells? Makes sense to me that if when you hit a surface and it makes a low frequency thud (like the trunk lid) then that area's likely to vibrate in that frequency range but when a piece of metal makes a solid "tink" sound, why waste vibration dampening on it?

 

it also helps with sound insulation. keeps road noise out too. it's good in the doors because it helps improve bass response.. i did mine not to get rid of rattles, but to improve sound quality. just picture a speaker in a paper thin enclosure as opposed to a speaker in a 3/4in mdf sealed enclosure

 

rickso03

i learned this the hard way i spent so much money doing the trunk but that is not making any difference now do the trunk lid and now we are talking!!!