according to NorCal Nick, rear shocks are recommended especially if you are going over 1" block. If you are going to do it, do it right and get some better shocks too. The stock ones suck, unless you got the factory bilsteins on. I believe Nick says that he gives 2.5" blocks with a 4" lift. I have 1.5" blocks with the cognito UCAs and stock keys. I still have room for adjustment. Of course my truck is slightly different from the NBS, but not much.