Grimeca disc brake conversion, supposed to be pretty good, at least a hell of a lot better than the original drum - which ain't much I can tell you.
I can see the aftermarket exhaust; what has been done to the engine?
We run a PX80 here, too. I bought it for the kids when the third one was 16 (now 32). The fourth, my son, still uses it as do I when he lets me (he says I break it). I pay for it but that is the limit of what I am allowed to do without him.
Over the years we have completely rebuilt the front suspension using industry (INA) needle bearings and making our own races to fit these so that the cages can be exchanged at any time. originally I had ordered the parts from Piaggio and got a box full of nonfitting items although they had the proper parts numbers. It turns out there are two or three different swing arms, different in such details as bearings but all the have the same parts numbers. That has also to do with the fact the that the PX80 was built in here in Augsburg, not in Italy.
Whatever
We fitted Bitubo gasstruts front and back as well. The handling (abysmal with a Vespa to begin with) was greatly improved and the front has needed no attention since then.
Since then we have fit a Malossi 160cc kit with the 24mm SI carb from the T5 (no oil pump) and JL Pipes exhaust. The carb got a K&N filter directly on the carb box. I did not allow him to change the final drive ratio for a higher top speed: 60mph is more than fast enuf for a Vespa. But with ca 15ps all you need is top gear and throttle in city driving, torque like a tractor.
10 yeas ago, we had a siexed up piston due to malfunction of the ol pump; th the shaft had siezed up on the crankcase. At that time we threw out the oil tank and have been running 1:50 full synthetic since then.