What are the benefits of an uprated radiator cap ? Thanks

 

Basically from what I understand higher pressure rated caps = a higher boiling point.
Increasing the cap pressure will increase the boiling point of the coolant but too high a pressure might cause undue stress on the radiator or header tank and cause premature rupture. I'm running a Buddy Club 1.3kg "race spec" radiator cap at the moment but STI, Zero sports and others do a similar cap in the same rating (£25-£50 odd) and this is working fine for me with the standard radiator & pipes still.
The higher pressure in the radiator causes the coolants boiling point to raise thus increasing cooling efficiency but TBH you will probably not notice the difference. (also aids with high ambient temperatures, high coolant tempertures and high altitude conditions)
Hope thats helped, Gareth