Front uca and spring contact is more of an issue on the KK I believe. With the stock uca and a 2" lift I had contact, with aftermarket uca's it would have been alright. With more of a lift, even with aftermarket uca's, you would have contact again. This is why JBA uses coil-overs, the spring is a smaller outside diameter and prevents it. Digger had a normal setup with his first JBA 4" and they lasted barely 4k miles. On the rear end with more then 2.5" of lift there is too much flex and the driveshaft will hit the gas tank skid. You could remedy this with 3" bumpstops but then your bumpstops are sitting on top of each other, you would have no up travel and an absolute terrible ride. So you would have to get 4" springs for the rear. I still had contact issues with driveshaft and had the track bar farther to one side, meaning the axle wasn't centered. I ended up having to get a custom driveshaft made anyway because my u joint has already started going out.
