game does automatically enough.
it upgrades your car automatically to any class you instruct it to, while keeping stuff as even/neutral as possible. from which point you can take over and finetune and/or change.
its a good system.
now I dont claim to be the end-all-be-all forza motorsport tuner (
), but can say I have a pretty good understanding of basic things. its just too much to write down, so again anytime you want hit me up on live and we'll talk about it