I use a needle proportioning valve and a single master similar to the one above. If I did it again I would use a second master and a delay bar as mentioned. Reason being, the restriction the valve provides on the pressure, also delays the return flow. So if you only want to run one master, a ball valve to turn it off or on would be sufficient. Unless for some reason you want to drag the left front after you let off the brake pedal? I also have the older version with the .750 piston in the caliper. The newer ones have a 1.00 I am pretty sure, for more braking power.