This is not an answer to your question; however, I also bought a G37s Coupe recently and have bough few parts for it. Dealers aren't very friendly with mod especially if your car is still under warranty because if there is a faulty they won't cover it and blame the aftermarket part that you purchased. However, there are few mods you can add, but once you start adding "power" mods such as changing exhaust and air intakes that will void the warranty. I decided to start my mod list by changing suspension, brakes, adding sway bars and few other stuff and leaving all the power mod towards the end of my warranty.