For example, last night i got bored and Gifted a car to Lilpooh21186, he told me it handled really well. Well it was simple i made a civic ek and boosted it very cheap setup nothing crazy.
But then i used my phones program and to use it you must have full tuneable parts, so Full Suspension upgrade, both swaybar upgrades, brakes (optional, if u have money why not), and the race differential.
in this iphone app "Forza Tune" the full program not the "lite" version u get a little input calculator. It asks the drivetrain, FF, FR,FA,MR etc etc, then the weight, weight distribution, tire width both front and rear, then the aero dynamic downforce.
After u plug all of those in, it gives u a full tune that u can plug in from tire pressure, to caster, spring rate and the brake balance.
Now right out the bat, the "basic" tune is really nice. But if you want a stiffer setup or a softer setup there are little "tips and tricks" to doing so when plugging in the original inputs, like adding 100lbs to the calculator so say your car weighs 2500 you say 2600 to have a stiffer setup. Or you want more oversteer you change the weight distribution more to the front and it gives you a better oversteer car.
For me i have noticed great improvements in the cars ive tuned for fun, its a nice little app for 2-3 dollars or w.e.
if anyone wants a tune for free give me your gamertag and ill send u a gift car thats tuned providing u giv the car with the parts or at least u pay me for the parts im kinda broke (in game...and real life...) haha