aleoplurodon

I recently threw my Hertz SPL Show 15 cubed at 5ft into my 1997 suburban and it rattles like non other, both inside and out. the car is in great condition its been kept in a heated garage and almost all the miles on it are highway so it isn't a question of the quality of the car. I am looking to deaden some of the excess sound and i'm a pretty hands on DIY person so i was planning on installing it myself, but was looking for something that would work good as a sound deadener that i could pick up at home depot or somewhere similar, dynamat is just too expensve. I have heard that ice and water gaurd works good, also aircraft insulator. if you guys have any better ideas please feel free to comment