I do not know the metric values as I have always used pound value caps. To fascilitate the movment of coolant from the water pump to the radiator the lowest pressure possible is best. I use a 7 pound cap and have a heavy duty water pump.That raisess the boiling point by 14 degrees to 226.
People think that a high pressure, as used by NASCAR, 27 pounds I think, is better but that will cause internal resistance to the system. The water pump pushes the coolant in a RWD car a very short distance compared to the Mangusta.
DICK RUZZIN