see and clear codes, different tunes for different grades of gas, set rev limiter, change fan operating temp, set top speed limiter, recal for tire size and or gear ratio change, change transmission shift points, change shift firmness, have had a couple years, 02-04 gt, cobra, you can really feel the difference when u change a few things, complete with instruction booklet, real easy to use, it asks u questions after u plug in and u answer yes or no, email me please, i cant post pics here for some reason, i have a couple pics i can send you, cliffcrays@yahoo.com, thanks for looking