A rubber bed mat weighs 40lbs? Dang! I guess it makes sense though.I have a 21 XLT 4x4 model and I had the Eibach's put on the rear as well and that did make some noticeable improvement in the ride. I tried putting a couple sand bags in the rear for weight, but I didn't like it (can't remember why LOL) so took them out and decided to try a rubber bed mat in the bed instead which probably weighs about 40 lbs., and that seemed just enough.