Coolant flow

Well aware of that. But with today's modern ultra efficient radiators, there's just zero need for a high pressure cap.

Definitely wasn't aimed at you, but the topic. I know you already know pretty much all of that :P lol.
I think we're saying the same thing. Only reason for a high pressure cap (over ~12lbs) is to crutch a marginal system on an all-iron engine. Between better tuning and better radiators/pumps, the cap is no place to look for system gains - even with an all iron motor.