I am trying to find the exact center of grip on my ball. I located my PAP but I am not sure how the center of grip is measured. Do you measure using:

a) the center of the holes where the drill bits are placed?
b) the edge of the finger and thumb holes (where my fingers and thumb touch the inserts) or
c) cut to cut?

If it makes any difference, I use finger and thumb inserts. Any help would be greatly appreciated. THANKS

Yep, the gripline center runs from the middle of the finger bridge straight down through the center of the thumbhole.  Then you can measure either the distance cut to cut or hole center to hole center between the thumbhole and fingerholes, and take half of the distance to find the center of grip.