I've thought of that, but at this point I feel that pushing an 8,500 lbs truck down the road isnt really gonna see much gain with the can. I could be wrong though... wouldn't be my first time :)
It will help, but like everything else it needs to be adjusted/tuned to the situation. An 8500lb truck will not need the same amount or curve from the VA can as a 2800lb duster.