I installed the Lippert kit on both axles about four years ago. It made a very noticeable improvement. Shortly after install drove down an old county road that was concrete with a light chip seal overlay. Bumpy, bumpy, could barely feel in the cab, and zero feedback from the 5er.
Due to clearance issues on the outboard side of the frame, mainly slide drive system, I mounted inboard.
This required moving both the galley drain line, and the gas line inboard about 3" to 4" both easly done.
Moved Drain line on drivers side.
Moved gas line on curb side inward about 3" to clear shocks tubes.
This is the moved gas line to clear the shock tubes.