The new HD springs should help a lot. Those are pretty old springs, if they are from 2000. I have a 2008, when I first got (used) it, it would bottom out with just me on it hitting some bumps. Although I'm 6'3" 290lbs. With the new spring it would compress maybe an inch awhile sitting on it. They have loosened up a little more over the last year. They compress about 2 inches when I'm just sitting on it now. If you swap out the rears rent a spring compressor to get them apart, makes life a lot easier. You may want to do the fronts right away also.