Downloading the program from personal computer to the tuner was a little complicated, but the set up in the vehicle was easy. It does make a difference in performance, at least with shift points and acceleration are smoother in performance mode, which could be less desirable if you prefer the harder feel of acceleration pushing you back in your seat with a stock G37. Upper end torque is increased, giving more passing power at higher speeds. Overall it's a good product
Easy to use
Received my programmer a few weeks ago and installed on my G37S as soon as I got home. Very easy to use, just follow the directions. On-screen prompts pretty much make it idiot-proof. I did notice there seemed to be a slight power increase and torque increase. Wasn't huge but helped. Will probably soon be installing a Stillen Gen 3 Intake to make additional gains.