I know this sounds old fashion but you might have to go even lower on your pinion. Take your car our in the street and try this. Measure off the distance of your longest straightaway (from your track) on the street. Then run your car through that measured distance and listen to the motor if it has topped out about 2/3 of the diatance then you are close. I know your car is real fast with those large pinions but that speed isn't needed for the size of track you run.