With a few exceptions such as as taking lots of wing off at Monza, changing the setup won't improve your times by seconds, an improvement of a few tenths is more realistic. However, changing the setup can make the car more predictable, allowing you to push with more confidence. .....
I reckon you have to get to the stage of 'pretty good' before the set-up's matter too much, as long as they aren't miles from where they should be.
The set-up is never going to compensate for getting the wrong line, brakung too early/late etc. etc. etc.
I agree with the Shark consultants
that its mainly down to the driver and the driving technique. Setups are very much a personal preference whats fast for one driver may not be fast for another - everyone has their own driving style, which the setup may not suit.
Like Aagramn says the one thing that setup has a big effect on though is the consistancy of the car over race distance. Managing the tyre temps with camber and pressure changes will greatly affect the temp of the tyres. If they are getting too hot then they'll wear away pretty quick, resulting in a big fall off in times, or just falling off full stop.
So if there's one area I'd recommend to play with its the tyre pressures and cambers - its pretty much all I ever change.
Drive 5 laps on the tyres before even thinking of looking at the temps though.
