There are better kits out their then procomp. First, let me ask you why you want to go 4"? That is a lot of lift, and you would have to change a bunch of parts to run 4" safely. I would highly recommend looking at Rock Krawler and Teraflex 2.5" kits. You can run 35" with both kits no problem and you will get a more complete kit. Also, the Procomp kit does not come with adjustable control arms or trackbars which are crucial for proper alignment on a 3" or higher lift. Plus, procomp kits are known to ride stiff.