I assume your talking about rear coil springs. Yes I have and you gain a little bit but the overload springs are what make the most difference. Once the overload springs touch you can just about put anything in the truck and the bumper height wont change. The coil springs are a bolt in swap. Another option you might consider is air assist bags. These are air bags that fit inside the coil spring and you fill just like air shocks. They are available from JCWhitney or your local truck accessory store.
