OK, I have approx 6" lift, rear XJ44, RE1462 pack and 6* shim, sye, rusty's 6.5 coils up front and no vibes on 33" x 12.50 mt/r's on 4.75" BS wheels. Have a set of 12" travel bilstein 5100's. Without boring you with all the math, I end up with only 3.5" of up travel and about 8" droop...