I have barely driven the car but the brakes felt great. I have been driving my 74 Euro Pantera for two years with a gutted 01310A and it stops well. It has stock brakes. I recently inspected the rear brake pads and observed a significant amount of wear on them. This indicates the rear brakes are getting well used. About 1/3 of the pads are gone in about in 2,000 or 3,000 miles.
I am thinking that most of these valves in Panteras are not functioning because the piston is rusted and stationary in the valve body in the open position and simply acting as a tee. There is a rebuild kit for the valve but there is usually so much pitting on the piston and valve body that the valve leaks once rebuilt. When the piston freezes it takes a lot pounding to drive it out.
Wilkinson is emphatic that the valve was never intended to affect front and rear braking performance. He explains that its intent was to reduce pulsation in the brake pedal when the front rotors warp.