The Max Energy allows you to adjust the speedometer/odometer to match rearend gear ratios from 2.73:1 to 4.56:1 and tire sizes from 23 to 30 inches in quarter-inch increments. You can also change the temperature at which the cooling fans turn on (stock, 180 degrees, or 195 degrees). Another feature allows you to raise the top speed limiter to match the speed rating on your tires (up to 255 mph), and you can adjust the rpm limit up or down by up to 500 rpm. It also allows you to read and clear diagnostic trouble codes (DTCs), return back to stock, and upgrade to new tunes from the Internet. There is also a provision to change shift points on vehicles equipped with automatic transmissions.