Bully Dog Power Programmers / Tuners allow for increased horsepower & torque, adjustable vehicle parameters, & extensive engine monitoring. Easy-to-use handheld & touchscreen devices connect to your OBDII port and allow you to adjust parameters such as axle ratio, speedometer calibration, tire size, transmission shift firmness, transmission shift points, global rpm spark, pedal response, idle adjust, mass air flow meter / sensor (MAF), speed limiter / governor, DOD (Displacement on Demand), fan control, air intake (disable check engine light), rev limiter, traction control, TPMS (tire pressure monitoring system), and much more. Pre-loaded tunes are included for many Ford, Chevrolet, Chrysler, GMC, Cadillac, Dodge, Nissan, Infiniti, RAM, Lincoln, Toyota, Mercury & Jeep vehicles. Custom tunes are also supported. DYNO Proven tune files will unlock new levels of power and acceleration. Monitor your engine parameters, read & clear DTC's (diagnostic codes), and tune your engine for maximum power output or optimal fuel economy. Gas & Diesel vehicles are supported. For gas vehicles, each tune is based on different fuel octane levels (87, 91, 93). Diesel tune files allow you to tune your Super Duty or Duramax turbo diesel truck for various levels of power gains or enhanced towing capabilities.