I didn't think about that but that isn't true for all bovs, some are directional which is actually what I had in mind when I made that statement. I did however think about the restriction, and I'm not suggesting an air tight enclosure. Something that will simply keep the oil from spraying everywhere. A box for example, or cardboard taped up in the right places.Well, clocking the blow off valve wouldn't do anything. It's a round valve over a round hole. Capture wise, you don't want to put something around it because its purpose is to flow to atmosphere without impedance.