Part of your spring stiffness could be your shocks. They might be bent or just two stiff. Pete and I both have 5 pack leafs and I for sure am happy with the amount of flex I have. Try jacking it up with your shocks attached (towards the outside of the axle, maybe under the leaf sting plate), then do it without the shocks. If your shocks are bent, then it will not flex as much, which could contribute to a stiffer ride.