The Allison 1000 has proven itself to be a stout unit behind the formidable Duramax powerplant. However, as power is increased over stock, weak points quickly rise to the surface. ATS addresses the inherent short-comings to offer a robust setup for your Allison 1000. The ATS Stage 4 Allison features: ATS Five Star billet torque converter, featuring five lock-up clutches, a billet 12 bolt cover, mixed flow stator and custom stall speeds ATS Co-Pilot Transmission Controller ATS Billet Flex Plate Proprietary drum and piston modifications ATS C1-C5 custom CNC?d steels and proprietary clutch pack material Additional pump modifications for even more line pressure than Stage 1-3 Packages Modified A&B Trim Valves New gaskets and seals ATS Deep Transmission Pan featuring a 5 quart capacity over stock, finned design for heat dissipation and a magnetic drain plug By increasing the capability of the torque converter, clutch surface area and line pressure, the transmission can hold 200% more torque than stock. The result is a setup strong enough to handle aftermarket fueling, turbo(s), tuning and the intensity of drag racing, sled-pulling or dyno competitions. Yet, it is still smooth enough to tow and daily drive. ATS Extreme Allison Packages include proprietary modifications to the drums and pistons. We have found these modifications necessary when power goes over 700hp at the tires. In addition, the pump is also modified more extensively for increased line pressure. When coupled with the Co-Pilot (standard on all Extreme Packages), line pressure in excess of 300 PSI is achieved ? which is needed to prevent clutch slippage. The Stage 4 features the addition of the ATS Co-Pilot Transmission Controller. The controller dynamically raises line pressure electronically, for additional clamping force on the clutch packs. This prevents slip under high horsepower / high torque situations, such as drag racing, sled pulling or low-speed trailer towing. Shift firmness can be adjusted with the push of a button, so the driver can adjust shift feel in a matter of seconds. The Co-Pilot is designed for trucks at any power level, but becomes crucial at 600+ hp at the tires. The Stage 4 also includes the ATS Billet Flex Plate. At power levels over 600hp, the factory flex plate can crack or break. The focus of the ATS Billet Flex Plate is to absorb more torsional load from the crank, thus resisting cracking/breaking as power transfers from the motor to the transmission. As with all ATS Transmission Packages, the transmission is covered by a 5 year / 500,000 mile warranty.