go roam the streets and press start(to pause) then press the pad to the right and you should see performance tuning, thats pretty much it.(you can't really really change gear ratios like say GT4, but you can "up the boost", add bigger nitrous shot that runs out faster, and tune gears for high speed or normal or low.)
1993 nissan 240sx hatchback(stock) <<drifter, straight liner, road courser
"Horsepower is the force that determines how fast you hit the wall. Torque is the force that determines how far you take the wall with you after you hit it."
"Horsepower sells cars, torque wins races" - Carroll Shelby
"Real cars don't make power at the front wheels....they lift them."