My acceleration from a standing-start has never been phenomenal, but I always pedal to get the 'ped moving more quickly. I don't know what to compare it with since I don't ride other mopeds, with the exception of Fred's, which goes like a bat out of hell. Of course, he's got a continuously variable transmission (AKA "variator") which allows his bike to use a much lower drive ratio than mine when starting out.
Top speed used to be around 25 MPH. With these mods, I'm topping out at about 32-33 MPH. I know this by having Fred pace me because my own speedometer reads 6-7 MPH high (at least it was until today, when it stopped working entirely.)
I anticipate another couple of MPH as a result of putting in the right jet. The smaller rear sprocket, still to be identified, might add more but it's hard to say right now.
I'll email you directly with the info on my Italian contact.