I think Subaru engineers went a bit off the deep end with the oil pump volume. My Z06 stock oil pump only puts out around 7 to 7.5 GPM at 6500 RPM. High performance after market oil pumps for that engine put out around 9 to 9.5 GPM.
It would still be interesting if someone could actually measure the oil temp and oil pressure on one of those Subaru engines to confirm is it matched the service manual specs. My Z06 had oil temp and pressure digital gauges, and I plotted the oil pressure vs oil temp vs engine RPM, and when the oil was hot (5W-30 Mobil 1 at 200F) the pressure would not get high enough to hit oil pump relief. And I'm sure the flow would not have put the filter in bypass either.
What year is your Z06 ?