Need help understanding regulators

I'm a bit confused with something I heard about the new Marauder Field & Target. Basically, it was said that you can customize the power level of a regulated air rifle with the common hammer spring and valve adjustments many with Marauders are familiar with.

How does adjusting the valve or hammer spring give more or less power when a regulator is being used?
 
When regulator is used, working pressure in the plenum is held constant through the shot cycle.

When hammer strikes valve it lets air escape. By adjusting spring tension you can control how much air gets to escape before valve closes.

But this range of adjustment is limited. Maximus power achievable is related to plenum size and working pressure.

If you adjust for low power, it will increase as pressure drops below regulated pressure because valve will have less resistance when opening and less force when closing.