For the person who has everything including a paiinfully slow Vespa. Polini Big Bore Cylinder Kit for Vespa 50cc 4 Valve engines, like the one in your pokey Primavera or sluggish Sprint. Perk that Vespa up and stop Flintstoning away from stop signs.
All Aluminum, with a Nikasil cylinder liner, and an excellent value. It's Winter, and if you're not out riding, you might as well be taking your Vespa apart in the Garage.

https://scooterpartsco.com/polini/polini-cylinder-kit-88cc-for-piaggio-vespa-aprilia-4t-4v

And of course, we have the Malossi Big Bore Kit for 2 and 4 Valve engines.

https://scooterpartsco.com/malossi/01-malossi-master-part-list/malossi-88cc-vespa-4-stroke-big-bore-cylinder-kit