The transmission in a scooter (SW included) operates a lot like a mountain bike. A MB will have three chainrings in front (small, med and large) and eight to ten sprockets in the back (large to small). Small chainring/large sprocket gives the best take off or hill climbing ability. Large chainring/small sprocket keeps the RPMs low for cruising. The weights control the shifting of the transmission on the Silverwing.
Lighter weights keep the belt from climbing up the face of the variator as quickly. This keep the front "sprocket" smaller, allowing faster acceleration.
Heavier weights cause the belt to climb faster, slowing acceleration. Some feel it will help gas mileage. Lighter weights will probably hurt mpg.
The weights are either "rollers", "sliders" or "pins".
Rollers are round weights that are thrown outwards as RPMs climb. In theory they roll outwards. In reality, they tend to slide outwards, which causes wear and creates flat spots and diminished performance.
Sliders are an attempt to solve the flat spot issue. They start life flat, and slide outwards. Their shape allows them to push the two halves of the variator together a little closer, making the belt ride slightly higher and increasing top speed. Their lighter weight usually help acceleration too. Sliders are made by Dr Pulley. Dr Pulley is currently moving from Taiwan to Germany. Buggypartsnw.com sell their products in the USA.
Pins only come with a J Costa variator and will ONLY work with the J Costa variator. A JC provides much improved acceleration and is generally smoother than stock. It also tends to wear out. Don't expect 30,000 miles out of it. I still like my JC and will use it until its trash.
Youtube will have videos demonstrating sliders and the J Costa variator.
HyperPro springs will improve handling at the cost of some comfort. I am still happy with mine.
Hope you're enjoying your new ride. Glad that your MC friends appreciate it also. They will probably appreciate it even more when you get caught in a sudden downpour and stay mostly dry.