Enlarging PRP doesn't always help

In my limited testing of changing only the valve job from a 45 to a 50, the results were less lower/mid-lift flow, and no gains, or even a slight loss at the higher lifts.

Keep in mind these were tests done at the customers request, on a head that had to be usable after the testing was done.
So, pretty limited.
But I saw no magic from the 50.
I’m not saying it doesn’t work, but I can see where it would take actual R&D to be able to exploit it.