Great stuff

I have been looking into sound deadening material and found a great product called you guessed it "Great stuff" it made to seal cracks in rustic basements but it does a great job inside of boxes. It comes in a large aerosol can and sprays out like caulk but then expands about 2 in. Its airtight and water proof, the cells in the foam are closed cell so you would have to make your box bigger to accomodate for this. Another good thing about it is you can shape it with a razor. I have found that it does the job quite well.-Matt

It's also great for  rattle deadening in back decks, A pillars, etc...anywhere you can get the foam into./NyxBass