We offer all sorts of check valves for the PCV system as noted above, inline barbed makes so much more sense than AN fittings. They are designed to simply go inline of any -8 or -10 AN hose. So why waste the money on two extra fittings. Run your hose, cut a section the middle and add the check valve pointing in the right direction. If you have our PCV set up, or valve cover or both, it becomes even easier, as we have a -10ORB check valve that will screw into any hole on the system. An OEM valve is considerably more reliable?What makes you say that. The opposite is actually true. Also, the OEM valve has a TINY orifice. When you are upgrading your PCV system going external. You want to completely remove the stock PCV valve to gain maximum venting, We have PCV routing guides for everything. You can plumb the vacuum relief in no problem. Also, a stock valve cover would be pretty easy to drill, and tap for -10ORB its just a standard thread. the O-ring will seal on the outside. I attached the routing guides for people, this is not rocket science people tend to over complicate PCV operation.
As for the explanation as a BOV, that's really confusing things for people. The name implies EXACTLY what it is. Think of an air compressor, you have a pump, a tank. If you turn the pump on with nothing to check pressure it will just build pressure until something blows out, a hose, etc. Now add a pressure relief valve to the system that is set to open at say 150psi. When the tank reaches 150 psi it opens venting the excess pressure to avoid damage. Now think of your crankcase as the tank and your vacuum source as the pump. If you leave it unchecked it will just provide vacuum until something cannot hold it, usually its the seals you just start pulling past the seals, (whistling sound) now add in the vacuum relief valve, when you get to 10,12,14" it will simply open, and hold vacuum there protecting the crankcase from too much vacuum. It's very very simple.
Chris