Just compare it with the T-2C pressurization schedule on page 2-29 of the Buckeye flight manual.
Lets put it another way. Take a T-2C and remove the LOX system altogether and install an OBOGS system. Now lets assume after a few hours the part of the OBOGS system that is supposed to absorb nitrogen fails completely and the system is delivering only pressurized air through the mask. How would you even know the system has failed if you are at an altitude in the mid-twenties or below? In the T-2 you still have an 8,000 foot cockpit up to 23,400 feet and you have to exceed 26,000 feet for the cockpit to go above 10,000 feet. In the T-45 anything above an aircraft altitude of 14,000 feet means a cockpit altitude above 10,000 feet.