Actually, with the Diablo hand held you can also get custom tunes from tuners that use them and have full control over you ECM vs. going with a tuner using HP Tunes or some other one time program. There are also online tuners who will take your log files (actual data collected on your car the way you drive it) and tweak the Diablo tune to optimize it for your car.get a custom tune from a good tuner. you will get so much more out of the tune.