X2 on Rays comments - the disc brakes sure tame the beast when it comes to stopping.
How are you connecting the booster to the pedal assembly?
That porp. valve looks identical to the one I bought from Master Power Brakes. I was told it is a combination valve and already has the 2lb residual valve built in. Might want to check on that. Master Power has changed their wording on the valve info though and it no longer says it includes the residual. I did not use a residual valve on mine and mine works great.