Sound deadening

Chandler

http://www.dynamat.com/car_dynaxorb.htm - this might actually IMPROVE your sound, but that is open to debate I (or so I've read - no personal experience).

But otherwise damping will not actually IMPROVE the quality of the sound coming out of your stereo .. all it will do is quiet the noise from the road or from vibrating parts of your vehicle.  Unless your car makes audible rattling noises or is unusually susceptible to road noise, you might be wasting your money doing the entire thing before you even install your stereo. - especially a large vehicle like that! 

Anyway .. don't go drop hundreds until you've heard your system or like spending money.

Actually.....when you cut the rattling out of the vehicle you improve the acoustics of the car which translates into better sound

 the best way to sound deaden a car is not to just cover everything in dynomat. You don't have to go that far. start by getting your subs and amp in the vehicle where they will be installed. Get your hands on a cd that will run a bass wave sweep through all the frequencies. start with the lowest freq. and find the parts of the vehicle that are rattling. Deaden just those areas with dynomat and expanding spray foam. Hit the next bass frequency and do it again and again untill you've gone up to around 160hz. That should cover you through the midrange. What you are doing is finding the resonant frequency of your specific vehicle. It may take some time, but it will produce exactly the rock solid result you are looking for, ad ya won't have to spend alot on dynomat. Good luck. You can also use "peal and seal" instead of dynomat. you can buy it from home depot or lowes for WAY less money.

if its jammed force it - if it breaks in the process it needed to be fixed anyway