You need to fiddle with the gearing so that it's tall, but not so tall that you won't accelerate to the 300mph target.
Adjust the downforce to a low setting.
Lower the ride height, and soften the suspension.
That's all I've got, anyone going to correct me?
Any outside chance anyone know of a good setting for the GNX? I am fairly confident it's a very very long shot, but the closest I can get is 215, but that's with a bottle. Yikes!!! Any advice *not* involving ditching the car would be most welcomed. ;-)