you guys that have done the back wall with the deadener how much does it actually quiten the noise from the exhaust and the tires. would it be considered a night and day diff? i ask because i have straights on my truck and they stop about a 1' or 2' after where the cab and bed meet and its really loud going down the highway. i have a 3/4 piece of mdf back there that covers the entire rear wall from top to bottom and side to side. it helped make it a lot less noisy but it still needs something else. i have to turn up my system about half way just to drowned it out. but if it works really well and helps out ill do it to my f150 and probally the noisy stroke to.

 

i put my dynamat in back there before i had my exhaust (flowmaster 40) so i cant give a comparison, but my exhaust isnt very loud even at wot. mine does go all the way out the back though so im sure yours would be a bit more noticeable. the only mud tires ive had on my truck were stock size cooper stt and i could barely hear them.

 

I put 2 layers of Raamat across the whole backwall, then the boards to mount the amps ontop. Covering the passenger vent REALLY decreased exhaust noise. I have a 9" Borla muffler with tips run out the back, so not as loud as your but still pretty loud without the deadener. Now with the windows up, my truck sounds nearly stock inside the truck under 2500 RPMs. I also have 35" mud terrains and its super quiet as long as I keep it below 75 mph.

 

so the deadener actually works to keep the road noise out.