The pressure vs flow relation to level of assist is difficult to understand.

Looking at the Heidts valve patent, I understand it is a return type pressure limiting valve that is independant of flow. However, reducing pressure will reduce flow.

KRC pumps have swapable valve fitting with different flows.

Both are intended to adjust the level of assist but one works on pressure, the other on flow!

I might be wrong but I think that when there is no steering effort, oil flows in the system at zero pressure, keeping the pump cool. when effort is required pressure is build up to provide assist.

From that logic, I think lower pressure will lower the maximum level of assist but low flow will reduce the rate of assist.

But since there is still a pressure/flow relation, I cannot say which is best to improve steering feeling.