Yup, Mazdaedit he tailors the tune to your specific car based on the data you send back to him per successive tune. The handhelds are the same but they're not tailored to your car. You won't have to send data back and forth to him, and you can flash to different pre-made tunes easily. Because you're not sending data back to him, it's not as aggressive of a tune, since he wants to keep an extra layer of safety buffer. What the actual difference in power gains there are between Mazdaedit and handheld tunes are unclear. I wish he'd be a little more descriptive on his website. But i'd imagine something along the lines of a 93 octane tune file from the handheld will probably net the same gains as a 91 octane tune from the Mazdaedit.