Please choose the size you would like. When choosing take in mind all other mods. Example when using 12gram or more weights use a 2000RPM clutch spring for better take off. Adjust the clutch, clutch springs and Torque Spring
MRP, NCY, Naraku or Plain Brown Wrapper brands they are all the same factory
Be careful where you buy--- the old trick of spray painting clutch springs is done by the dogs out there, I know all the tricks because I see all the scooters with this done.
Adjusting the spring tension on your clutch you can get the rpms up with the clutch and use heavier weights in the variator, use clutch springs and torque spring plus a heavy duty performance clutch for all stall and use 11gram in variator so you don't lose top end.