THIS SETUP IS FOR GT6 USING AN RX-7 GT300 BASE MODEL.
This is the setup I used at Autumn Ring for the MWM RC (Midweek Motorsport Racers Collective) GT300 event.
The oil needs changing to get to 510pp, and that is the only mod you need.
Spring settings are 15.09 and 16.14 however there is no 2nd decimal place.
Wing settings are 350 front and 375 rear as GT6 is GT5 values x10.
I'm not quite sure what auto-set top speed I used to get the ratios above, it is either stock or 20km/h higher than stock, so you'll have to do a bit of tweaking to get it right.
The gears are set quite log but 2nd gear is actually usable so the time lost down the straights is made back up in traction zones requiring 2nd gear.
Best lap was set in an online lobby with tyre/fuel depletion set to very fast. The lap happened on full fuel, and did a 1:14.865 during a race with slightly lower than full tanks due to pitstop strategy.