I've getting mixed reviews on whether or not to connect both ends of an oil catch or not. Some people say that you should plug up the hose to the intake and leave the 2nd plug on the oil catch open. Others say you should connect the 2nd plug on the oil catch to the intake to create a vacuum of some kind...? So which is right? I got a Cusco oil catch.

 

connect the oil catch can to the breather line coming from the valve cover. I don't think it matters if u have the other end off or connected to the intake as long as the intake it either capped off or connected (don't leave the intake open).