Here is another question. I used a product called ensolite in my car, It is a closed cell foam about 1/8 thick. if i remember correctly it helps in deadening outside road noise from creeping in. i used it on the floor and the doors of my car. i can't tell you if it made a difference because i never heard my sytem without it. My car sounded great. Would a couple of layers of ensolite under the sub help any?