This Metropolitan II is running a stock 70db muffler, but has the standard Metropolitan I Variator to increase the top speed, although the motor is hitting the Met II rev limiter near 7500rpm. If more power is made, then a CDI with higher rev limiter would be a good improvement.
***Note that the Metropolitan II has lower gear ratios in the transmission than the standard model (Met I), which are the same as a Ruckus transmission (~13% lower, 47/12 vs 45/13). These gears will limit the Met. II top-end speed compared to other scooters.
***Ruckus owners can take advantage of the higher gears from the Metropolitan I to get higher speeds (and less over-revs), thanks to the Ruckus bigger rear wheel!