but you have a line that goes from the VC to the turbo inlet, when boosting that turbo inlet is seeing a lot of vacuum as the turbo is sucking in air. That is now what is sucking the air out
when your boost gauge shows a vacuum condition, the pcv is open, and the air is being sucked out of your valve cover, and into your intake manifold. That helps get rid of any built up pressure in the crankcase.
well think of it this way, the whole purpose of this system is to introduce vacuum into your motor, to help suck out any pressure in there caused by blow by
