Find a big empty parking lot, and try some really hard stops. Do your rear brakes lock up too soon? If so, turn down the pressure to the rear brakes. If all four wheels lock up about the same time, you're good. Don't touch the proportioning valve. In an emergency stop, you want all four brakes working at 100%. During normal driving, you won't be able to feel any difference in your brakes, no matter where you put the knob.