I use a rubber grommit on the driver side with a pushin style breather on a tube extended a couple inches above the valve cover. I have a filter sock on the pushin breather. On the pass side i have a -12 hose connected to valve cover with AN fittings. I now get 0 oil leaks on top of my motor. Before this, after a spirted drive i would have oil running out valve covers and all over the valley tray. You need a way to vent the crankcase pressure and this set up works. Next option would have been a vacuum pump. No baffles in covers and rattle can caliper paint.