I checked several US and European car links and forums... no way to know what those valves are rated. They just say which valve is closing harder than another, but no ratings.

There are some manufacturers of adjustable BOV's (starting from $120). I'd go with one of them and adjust it to better fit the specific setup.

Some can be adjusted by a screw, some other changing the spring (they have then different colors depending on the rating).

If I have time I'll open mine and try to make it adjustable.