I am confused about this VCV setup you describe (thanks for helping BTW). I have one line that comes from the booster line to the top of the VCV (supply), then I have one that comes off the lower side of the VCV (driver side) that goes to no where (the one I am confused about), and then the only third one I see is the one that comes from behind the VCV (behind being engine side; slightly in the back toward cabin) that goes into the cabin. My fear is that THIS is the vent line, and the one going to nowhere somehow attaches to the amplifier. But I dont see where. I am lost, helpless and losing my mind on this. To boot, I just posted that I snapped the supply nipple off the vacuum booster line.