Malossi Variator Multivar 2000, famous and popular variator by Malossi, and deservedly so. 
It will provide optimum transmission of engine power provided you're using the right weights. You'll notice improved acceleration and take-off, and slightly higher top speed.
Malossi Variator Multivar 2000 for Aprilia/Piaggio comes with a torque spring ("Sport", white) and 6 roller weights 19mm x 15.5mm / 7.2g.