OK at what RPM you shift from one gear to the next has as much to do with trans. gear spread and the amount of RPM's loss / dropped after the shift as anything. A 3.37 first and a 1.99 second means a 41% drop in RPM after shifting. If I shift at 5750 RPM from 1st to 2nd my engine drops to 3395 RPM. The idea is when you shift from 1st to 2nd you want to have the same or more wheel thrust to accelerate the vehicle. Because the % drop is highest in 1st gear you will need to shift 1st at a higher RPM than the other gears.