Twistgrip's 69 F3 340 GTS Resto

There is no difference, vacuum is vacuum. I see a mix 50/50 of people running PCV or just two good breathers. You'll get a lot of different opinions. Personally, I don't think it matters much either way on hobby-type cars. I'm sure you change the oil way more often than your supposed to, and also don't do a lot of real short trips. So the oil heats up good and whatever moisture is in it burns off. In that case, oil has no chance to get contaminated with water which is a big reason why it might be good to run a PCV system under more "normal" (daily driver) circumstances. I have one K&N breather in each valve cover, oil gets changed every 1,000 miles, or one Summer (whichever comes first), and I have never had a single oil-related problem. Some will say I am crazy. That could be. I say do whatever you want!