For the performance enthusiast, PPE offers the Stage4 transmission kit. It will ensure that your Allison 1000 transmission can handle up to 850 hp at the crank (approx 680 rwhp) and up to 1,500 ft. lbs. of torque without damage. This kit is designed to handle a Duramax engine that has been equipped with multiple high performance modifications, such as performance chips, oversize injectors, and/or small nitrous kits. This kit includes PPE's Valve Body Recalibration Kit (recalibration kit does not change shift points, only increases clutch holding power), Converter Flow Valve and upgraded High-Friction C1, C2, C3 and C4 clutches with Kolene steels.