AFAIK in addition to hose etc. connections, there are (at least?) 3 variables that affect how efficient a PCV will be on a specific engine and state of tune:
1. high vacuum (minimum) opening diameter, with restricting cone fully inserted
2. low vacuum (maximum) opening diameter, with cone fully retracted
3. spring tension, which determines how much vacuum is needed to restrict flow
1. & 2. are strongly based on engine displacement
3. includes idle characteristics (hot cam, etc.)
I've never seen any of these listed.
