Each engine driven pump puts out 8.6 gpm at 2525 psi and the system pressure relief valve has the capability to bypass 16 gpm when it is fully open at 3850 psi. With that being said, you should never experience an overpressure of that much. For that to actually happen, you would have to have a pump compensator and system pressure relief valve fail at the same time. It must have happened because there is a procedure in the dash one for it. A friend told me that he had an overpressure while he was flying slicks at Rhein Main in the '80's. He didn't say exactly what that pressure was and nobody actually noticed the rudder booster pressure when the flaps were up.
My thoughts: The rudder pressure reducer should bypass enough pressure in conjunction with the system pressure relief valve to keep it between 1100-1400 psi. If not, the rudder pressure relief valve would open at 1600 psi and maintain no more than that pressure.