Carry Livin LIte 8.6 on 3500 SRW with no mods??

I carried a 4000# S&S on a '05 CTD 3500 with no mods. Your Timbrens are not installed correctly. They should not come in to play until the truck squats down under load. Best advice I can give is load the TC and try it to see if you need any additional support. No sense buying something you don't need.