jeffrey1 - really? Where did you get that information?
The only reason an A250 has such high oil pressure is to make the Q meter work. The lube side does not need high pressure but is subsequently designed to operate with it. In other words low oil pressure is a problem for the lube system as it is designed. I am not saying that low oil pressure is not an issue. The oil pressure is regulated in the engine and only needs to be adjusted to higher than the demands of the Q meter system.
The following probably sums it up quite neatly.
United States Patent 4690614
A torque meter is provided for use in conjunction with a layshaft having a forward and rear end and which is rotatably mounted in a housing. The layshaft is axially movable with respect to the housing between a forward and a retracted position while a gearing arrangement in mesh with the layshaft urges the layshaft towards its forward position with a force proportional to the shaft torque due to the helical cut of the gears. The torque meter comprises a body secured to the housing adjacent the front end of the layshaft which forms a chamber open to the front end of the layshaft while a piston is axially slidably mounted within the chamber. The chamber is pressurized with a fluid, such as oil, which urges the piston against the front end of the layshaft with a force proportional to the pressure so that the piston balances the layshaft against the axial force imposed by the engine. A fluid pressure gauge determines the pressure within the chamber which varies proportionately with the layshaft torque. In addition, a piston ring on the piston opens the fluid chamber to an opening in the body and a passageway in the housing when the layshaft moves to its rearward position, indicative of a negative shaft torque condition, whereupon fluid discharges from the chamber, through the passageway.
From memory on a 20 series the pressure equates to 1 PSI = 4HP at 100% N2. Any difference in N2 and these numbers will change.
As to the Jetbox high Q at flat pitch - most obvious is too much pitch.
If the passageway (bleed) is blocked or restricted your Q meter will read engine oil pressure or be slow to indicate less Q as appropriate.