ICON Vehicle Dynamics 2007 - Current Toyota Tundra 1.5 Inch lift Rear Leaf Spring Expansion Pack. Unlike traditional add-a-leafs that obtain lift height at the cost of stiffening spring rate and sacrificing ride quality. This new approach, full length Toyota Tundra leaf spring expansion pack, replaces all the factory secondary leafs while retaining the factory main and overload springs. This allows us to modify the spring rate to increase ride comfort, obtain lift height, maintain load and towing capacities, and increase wheel travel. By retaining the factory main leaf installation is a snap.