Don't go over a 1/2" shackle lift or you will have all sorts of driveline problems (search this bulletin board and you will see numerous posts cncerning this). Do a 1/2" shackle lift (shackles 1" longer than stock) and a 1" body lift. This should be OK for 31's, and your ride quality won't change a bit. You may get some fender rub during extreme compression off road, but it shouldn't be too noticable.