I ran the F1 series in this car and used stock settings with a few adjustments.
Dropped the suspension as low as possible, dropped ASM to 5 TCS at 2. Front down force at .70, rear Downforce at Max.
I tend to get quick on the throttle out of corners so I wanted the rear to stick to the road. Other than that I did little in toying with the gearing, LSD and suspension.
I do believe that this is the quickest car around a track in GT3.
Enjoy, however don't forget about the other 180 or so cars.
AO