If you set the engine up with the tank in a good position there will be no change when the regulator is installed other than you can run the engine right at peak because there is no mixture change from full to empty. Some complain that you can't get the engine much richer than about 250 rpm rich of peak. It is a demand regulator and won't supply much beyond the demand. Which is just fine since there is no longer a need for it. It will idle longer than you need, I've never tried to see if it would run out of pressure. Acceleration is of course clean and crisp without the rich top end. Lube is adequate at peak.
John at Iron Bay was not sure the regulator would feed a Saito 2.20, I cleared that up for him.
Saito 2.20 with Iron Bay regulator.