As far as pressure, what ever is on the radiator cap, is the MAX you should see... at idle, when heat and motion isnt a lot... there will be very little pressure....
AS far as transfer into the overflow... Hmmm... I havent noticed anything outta balance... but, its freakin cold up here, just started getting into the 40s....(and a 50s yesterday and today).....
ON a second thought, if you are asking this, I assume you arent getting squat for pressure, and purging into the overflow, you might wanna just get another rad cap.....
Chase