You download the program of choice. Takes about 5 minutes or a little less. Only one program at a time. Can't change anything on the fly. You are basically downloading a different ecm program with each power level. This is power at the ECM level, not at the sensor/"fool the ecm into changing things" level (change on the fly). The programs do more than just change the fueling. They change the fuel, boost, timing, etc. maps dynamically. Also, it changes torque management.