Clois,
I hope your not having problems with your new motor. I always use the high volume pumps, just a preference. You don't need sky high
oil pressure to protect your motor, you need good
oil flow. High pressure does not equal high flow and does not protect as well either. You might have high pressure
oil that stays stuck in your bearing too long and gets too hot. A higher flow rate keeps the oil moving better so chances are you have "fresher" oil on all your bearings.
This is just a suggestion, but if you have really low oil pressure you might have pushed out a oil plug in the galley. If you have break-in additives that will lower your pressure a bit too. A high volume melling pump should give you plenty of pressure. All you really need is about 20 psi or so at idle, but lower than that start worrying. As long as you have 20-25 at warm idle and it jumps up when you give it throttle, your fine. Cruising at 40 or 50 is fine. Seems like high pressure pumps put excessive stress on the cam and dist. gear for no real benefitial reason.
I've also heard that if your pump picks up a shaving or a piece of metal it can get stuck in the bypass. This would make your pressure go to nothing, and it's not uncommon for brand new motors to give up some metal (not alot, but some).
I hope my ramblings help.