check valve on both of the lines out of catch can. my issues came from removing the original passenger orifice and replacing with the 1/2" that Overkill sent. i know it sounds not probable with the aluminum valve cover, but it can be done, on accident ha ha. Over all the whole kit that was listed as brand name arrived as alibaba parts. except the K&N filter, and a precision turbo BOV (wave spring used but he left out the vacuum adjustment shims it should have had) i had to install some dramatic in line hose reducers. basically bottle necked with standoffs.
your diagram is spot on as i was told from tracey lewis. but they also have a new connector that supposedly increases the venturi effect at the pre valute connection. i couldnt use it because it is backwards for my installation.
https://youtu.be/CCvIqH8X1dY
i just found the intercooler he sent me ID marks and tracked it down. its scary.the advertisement says things like "can be successfully installed" "new plastic in glass fiber" the whole system basically needed replacement.