rear pressure low in system HELP

Thank you everyone so far. I'm still scratching my head on this one still. :banghead:

Question: Must you have a Proportioning Valve Disc / Disc regardless of having a manualy adjustable valve like I do? Can you have both? Should you only have one or the other, Why?

I have replaced the master cylinder that came with the Right Stuff kit with a "NEW" new master cylinder from NAPA. Right Stuff sent me a replacement booster assy. when the failure was the threaded eye bolt. The bold failed when bleeding the brakes (with one foot) YIKES! Check yours. Once I set the braked peddel hight, I installed nuts on the threads to help prevent a future failure. Adding support to the shaft. The replacement booster came in poor condition. Loose bolts, cotter pins not in safety and the push rod installed backwards......Huh!

Today I will install a 2 lbs. residual valve between the master cylinder and adjustable valve for the rear wheels, bleed, bleed, bleed and let you know.