Dear Friend: I don't know how you define "bumpy feeling," yet, I go to say W163's suspension is not bad considering its weight and H-frame. Perhaps, you may start your tuning at the tire selection instead of other more expensive after-market products. At the same token, you may also take a careful examine at the integrity of suspension and rings...depends on the vehicle condition. My vehicle traveled around 77,185 miles and I guess I got no complaint so far. The nature of question you need to ask is: What you need from this W163, to go off-road, on-road, or some sort of combination?
Dear friend: Just in case, if you are still not satisfied with all the info we have provided, you may log on http://www.whnet.com/4x4/dynamics.html for original design specifications and consider some after-market at tirerack. Just share some thoughts with you. After all, I can understand how frustrated you are.