Something to remember. Pressure=resistance to flow. You can get more by either adding volume to the same size hole. (keep in mind, the "hole" in this case is the oil clearancees around the lifters, the rod side clearance, and the crank journal to bearings) or you make the hole smaller and pump the same amount thru it. That's why the High Volume pumps were developed. To band aid engines that have a little wear due to normal use, but that are not worn to the point of damage. If Mike HAS the HV pump, and has a dropping pressure from when it was assembled. It's a negative change that shows damage somewhere. Again, assuming the gages are accurate.