GregF wrote:
... The O.E. valves are installed on the master cylinder and the stock brake line threads into the valve. The valve limits rear brake pressure until a set pressure is reached, which then allows pressure to go to the rear circuit....
I have read just the opposite in a few different places. This from the 944 FAQ about the factory proportioning valve:
Up to the point of the change-over pressure, both the front and rear brake circuits receive full system pressure, i.e., the pressure within the brake master cylinder. Above the change-over pressure, only a fraction of additional system pressure is shared with the rear brake circuit.