6.5 water pumps

[Kennedy]

I would really like to know if there is a true factual basis for why the 4 stud style water pump flows with a supposed huge flow bias where the thread on style does not. I would think that a picture should show immediate differences if there were any. There are 6.5 vendors out there that make statements about the 6.5L cooling system that they cannot prove. They may talk about testing, but provide absolutely no factual data or proof of how the tests were performed etc. They just make bold statements.