While your dealer is friendly try with him , i have s8 50cc 4t
and i changed the whole variator because of slow performance
now with polini variator i have better performance for 30% + 10% of cdi rpm derestriction
and i have to say its well spent moneys now i have 65 km/h (40 mph) top speed
and downhill 70km/h (43mph)
so if you want more top end you should tune it more
change the main jet size , change the pipe , the belt , and the clutch
so there is too much money and i won't ever spend that moneys
while you can sell your bike and buy 125cc if you have driving license