Right before you enter a race in GT mode, among all the icons displayed at the bottm of the screen, you will see what appears to be a red tool-box...That's what you will want to select. Then, on the next screen, scroll through all the different tuning options and the rest should be self-explanatory.
You must first buy the FULL suspension kitt, and full transimission kit, to be able to change height, and gearbox...
Then after that you go to that Red box, before the race...
