The car I have recently purchased has a valve cover breather on the passenger side cover, but also still has the PCV intact. Or Atleast it seems in tact there is a hose from the upper intake to the lower with a check valve etc. my question is should I be running both of these since my car is NA? I want whatever is best, would it be better to run a hose from the BC to the throttle body? Or is it ok how it is?