First what are you trying to achieve ? panel rattle , transfer noise , road noise ?
So many choices now like closed cell foam and barrier mats it all depends on what you are trying to achieve.
Dynamat is over priced and way over rated in todays market ! you are paying for a name.
Try silent-coat it gets a great rating from audio nuts over on TalkAudio or use 1 of the bass nutters own stuff from TalkAudio comes in 2mm and 4mm thickness and outperforms and under prices dynamt all day long.
pm me and i will pass you his details.