[Tommy]

The following is an academic answer that may not hold up to scrutiny from real drag racers, but here goes. Assuming traction is not an issue, acceleration is primarily a function of engine torque. Your shift point should be such that your RPM at the shift is just as far above your peak torque RPM as your new RPM is below after the gear change. For example, if your engine drops from about 5400 RPM in 3rd to 4000 RPM in 4th, you'll stay within 700 RPM of your peak torque in both gears. As you get to higher speeds, wind resistance and horsepower become more important, so higher RPM help.