I run 33's with an extra leaf in the front and a few extra in the back, giving it probably 2" of lift. For 33's, a 4" lift will easily be enough, and a 2" lift might work, depending on what wheels, tires, and offset you're using. I've seen these trucks clear 33's with stock suspension also, but every case is different. If you're going to use a knobby mud tire on a wide wheel definitely go with a 4".