Quick and very dirty CFD run on the Z

_ace_

This crude prediction isn't good enough to tell you anything useful, sorry. If it were right, the plots indicate very little positive pressure except at the very front of the hood near the bumper. (It also says the fangs are a good spot.) While I don't find that hard to believe, this CFD result isn't trustworthy--I didn't even look at all my assumptions, much less verify they're decent and the result is valid.

Have you thought of a test you could do without cutting holes? (I checked and Pitot tube systems aren't cheap enough to be worth messing with.)

You could always put a scoop on top of the vents for track days if it doesn't do enough alone. Use a bigger scoop if you need more cooling that day.