i have a 2" shackel lift on my YJ and it rides fine without any modifications, although it flattens out the leaf springs a little. I am in the process of doing a "spring-over" lift which is what a would reccomend for the YJ's. That way you can use the stock springs and you get the same ride (not as stiff as a spring lift) and you get 5 inches of lift. Although if you do this big of a lift, you need the following: a skid drop kit, drop pitman arm, brake lines, new spring perches, shocks, rear driveshaft, and a slip yoke eliminator. It will come out to about $800 worth of parts but you'll be ahead of the game compaired to a spring lift.