There was no change in performance and with the DB killer left intact the exhaust note was actually quieter than stock although a slightly different sound.
Top speed was 59 MPH (GPS) on most runs.
I then fitted the bigger 12" wheels from a 2020 Primavera 125 (stock were 11").
The bigger wheels made the gear ratios taller so acceleration was slightly slower with an increase in top speed. Uphill speed went down too.
I fitted a Polini Max Hi Speed 6 roller Variator with 12.5g weights and a replaced the stock air filter with a Malossi red filter which made the acceleration noticeably quicker and top speed cruising much better than when the Primavera was totally stock.
A few days ago I removed the DB killer from the Tecnigas GP4 to see how it sounded. To my surprise it wasn't that much louder just a deeper tone but what I noticed was that the top speed went up from 64MPH (after the variator swap) to 68MPH over several runs. At the top end the rev limiter kicks in.
Before and after sound of the exhaust
I commute a couple of days a week on the Primavera and now am able to overtake lorries which used to be a big problem when the Vespa was stock.
According to the exhaust manufacturer when the same exhaust is fitted to the Primavera 50cc 4T, removing the DB killer will increase top speed by approx 2-4MPH as the stock exhaust has a built in restrictor.
12" Wheel with DB killer fitted to exhaust (Polini Variator)
12" Wheel with DB killer removed from exhaust (Polini Variator)
11" Wheel with DB killer fitted to exhaust (Polini Variator)
