Depending on air temps, I would use anywhere from 0° to -10° to maintain rpm and build boost when staging (turbo). Procharged cars can use timing for smooth power management, and/ or blow off valve actuation for abrupt traction loss.
Timing is more effective with a blower than with a turbo. Reduced timing with a turbo increases exhaust heat, speeding up the wheels in the turbo. That effect is non existent in a procharged car.
Nobody I know uses any kind of boost control with blowers of any kind. It is all done with timing and fuel.
