I am trying to decide on using breathers or a PCV. I was wondering how much vacuum is needed for the PCV to work since I have a 660 solid roller cam? What do you guys think? I also have a Moroso breather canister with a -12AN line and fitting I could use as an option as well instead of regular breathers. I am getting ready to drill some holes on these new GM Perf valvecovers so I need to make up my mind. Thanks for your help in advance.