1999-2010 Duramax Kryptonite 2" Leveling Keys (KRKEY10)Cranking up the factory torsion bars and keys overloads the adjusters and limits suspension travel, creating a harsher ride and accelerating front end wear. This system uses special re indexed torsion bar adjusting keys that level the vehicle without compromising suspension performance and ride quality. With this kit installed, you can use up to 33" Diameter tires. Installation is straight forward and can be accomplished in less than two hours,