So, I've fallen down the rabbit hole called "buy things for Vespa so it goes faster!" I love it, but it's expensive.
This lead me to buy the Polini Venturi for my 20/20 SI carb.
I have the SIP fast fuel tap, Pinasco 2-port 177, and SIP Road 2.0
I have to say, I'm very pleased with the result. The kit came with a 115 main jet, which worked great.
I also got the SIP kit of performance jets (up to 128). They all seemed to work - even the 128.
There was maybe a slight hesitation in revs from idle to WOT with the 128. I eventually settled for the 122.
I've only just installed it. I'll have to check my plug in the coming weeks of riding.
Have any of you tried this? What main jet worked the best?