If you are looking to improve your handling charcteristics, I would suggest front and rear sway bars. I know hellwig makes some, I've seen them in Summit. I don't know the part numbers off hand, but it's worth a look. When you lower your truck you are lowering your center of gravity, which also will help with handling. If you are looking for ride comfort, the best system to go with is an air ride system. Other than that, most springs are the same, the more top end springs come from Eibach, I think they make lower rear leafs too. Of course, this won't be as good a ride as air ride, but it'll more than likely get you where you want to be. If you chose a rear shackle kit, you'll have to trim the bottom of the bed where the shackles come up. You just have to cut basically a box out of the reinforcing under the bed.