The ATS computer model for the Power Stroke has three positions: stock, towing, and extreme. Stock is self-explanatory. Towing gives you about 70 more horsepower and 140 lb-ft of torque (with the ATS exhaust system). This makes the engine very responsive and provides plenty of power for almost all situations. The extreme mode gives you 100 more horses (30 over towing), and 190 lb-ft of torque. But you really have to drive by pyrometer to keep the engine-gas temperatures within reason. The module also raises auto-tranny line pressure for firmer and quicker shifts, and it raises the speed limiter to 120 mph.