Is this stuff really worth installing in your trunk?? Does it really add db or spl?? And if it does whats the best out there ?? How much would you need for like a SUV or Mini Van ?? How many layers 1 or 2 ?? Any one with experience would be helpful !! Thanks
I does not add "SPL". It helps retain the pressure inside instead of losing much of it in vibration or rattling of body panels. Major hot spots are the doors, floor, hatch/trunk lid, and maybe roof. Also, don't forget to look into some closed cell foam to go with the sound deadening.
I have had great success with Second Skin Damplifier pro matched with Overkill. Once you have the major areas covered, search for any trouble spots then and you can double up in those areas.