[bishopts]

Yea the pcv Y goes into the crankcase and forces the air to go into the catch can. All others ignore that as a path of flow. Since it's the most important path of flow that is the closest to liquid oil going into the intake. Other catch cans only catch under boost blowby mostly.

If you could just close that hole completely then put a hose barb in the block off plug hole. Then use that as your primary vacuum source.