I'm sure it doesn't increase pressure, I think it does increase flow. I have done a little work around the oil feed to the pump on the basis inflow is good. That won't affect pressure either.
Some of my understanding on pressure and flow goes back to the '80s when I was involved with a software simulation model of an aircraft hydraulic system. We had long debates with aircraft systems designers and users (pilots!) about the effects seen on system gauges when different pumps and valves were operated! Somehow these people never see the same thing! Sometimes they wanted to force our model to do what they 'thought' they saw. And often we were able to prove they were wrong! And sometimes we were able to identify that they had given us bad data, for example the length of a hydraulic pipe installation was different to the designed pipe length!
I'm past even thinking about fluid dynamics, but generally, if you increase flow, say by opening a valve, you reduce pressure.
