The 4-pin clutch has flyweights without holes and has optional lightened flyweights with 2 holes. The lighter the flyweight the more agressive the clutch will become.
The newer 3-pin clutches has always a flyweight placed over the pin, if you do see the MRX5 clutch you have an example and you can cut a normal shoe to such flyweights. You can cut the 4-pin black clutch shoe so you have 4 flyweights with an hole at one side, this will make the 4-pin clutch an awesome clutch.
Speed is only fiction but a 130+km/h MRS4 is for real.