I play forza a bit, love the game and the paint feature.
Set ups are easy, do it yourself. press the toggle Y button to get a description of what each tweak does.
Mostly i have built Subaru drifting cars, setup with really strong stiff suspension and minimal downforce. thick racing tires and wide wheels and a lot of raw HP. When you learn to control the throttle you can really drift very realisticly in this game. Its like Gran Turismo with better everything.