gpm gives you speed and psi gives you power. Of course a lot of other factors must be considered, but as a general rule thats the case.
To increase speed (change state of motion) you need increased pushing force.....see Newtons first law...
摘very object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.
Increased flow is a result of the increased force...
Power is the product of flow and pressure. You need both of them to generate hydraulic POWER......it is OK to say that increased "gpm", or flow will give you increased speed, but you will need increased FORCE (pump shaft torque) to be able to increase the flow and speed