Modern Vespa

I should have taken pics, but didn't. I thought I had detected a bit of a rattle in my 2016 Vespa Sprint 50cc. Even at nine years old it is essentially a new bike, with under 600 miles. Everything is still virtually dust free, but it's spent a lot of time sitting.

I have the original pipe from my 2009 Aprilia Sportcity One 50cc 4T, which looks to be a very similar pipe. In fact, after removing the Vespa pipe yesterday they are practically identical.

Except for the diameter of the exhaust port.

Measuring the OD of the Vespa pipe, it is 3mm larger at the port end than the Aprilia. It also appears the ID I slightly smaller on the Aprilia, but certainly not 3mm. I would imagine this is because the Vespa is a 4V and the Aprilia is a 2V. My question for the gear heads is this : do they make a gasket that could be used to make up the difference so the Aprilia exhaust would seal up on the Vespa? Could I MAKE a gasket that would fill the space? If I were to swap pipes, would it be too restrictive for the Vespa? Would I be better off simply buying a Polini pipe or something?

Oddly enough, looking at the Aprilia parts catalog, the sketch they use of the exhaust looks much more like the Vespa pipe.