If you are running the wilwood m/c that is included with the Steel Concepts kit, you don't need to run a prop. valve. The only thing you may need is a pair of light weight residual valves if you are running rear drum brakes. The way it is setup you have got to replum your brakes anyway, b/c of funky fitting sizes. I contacted wilwood on this topic and that is what they told me to do. The line closest to the firewall goes to the rear brakes and the front fitting goes to the front brakes, and they split the ratios up in the m/c. BTW AGAIN THIS IS INFO I RECEIVED FROM WILWOOD, NOT SOME BACK YARD ENGINEERING I THUNK UP MYSELF, AND WHEN I SPOKE TO THEM ABOUT IT THE RECOMENDATIONS WERE MADE ON THE BASIS THAT MY CAR IS A RACE VEHICLE NOT A STREET VEHICLE.