[Don't Panic]

I just finished putting on a Mustang SVO master cylinder (four wheel disk brake car). It helped a bit, the car might be driveable now but it still doesn't seem good. With the car jacked up the rear tires will still spin when you lightly jab the throttle while standing on the brakes. The only difference being is that you can hit the throttle a bit more than before. When I changed the master cylinder I also removed the adjustable proportioning valve to make a direct line to the rear.