[ASV]

130/70-13 will fit well in a standard gy6 150 and 250 long case and it will bring the speed you start to climb rpm up about 7 mph
10 if you have a new belt. It also usually fixes the over proud speedometer problem with the Chinese scooter if you use it in front. I think it's the tire size the scoots are engineered for but the 130/60/13 makes a scooter a little quicker.
I have also found sliders are good for about 5mph over rollers

so if you add all that together it's fairly significant as they multiply against each other

you can get a real boost in launch capabilities if you cut the clutch weights significantly enough to have the clutch grab at a higher rpm
than the variator stabilize at but before it begins to shift