Modern Vespa

I have been enquiring locally to have my P150S Cylinder bored to suit an oversize piston but nobody is able to do it locally which means I will have to send the cylinder away to have it done. This gets expensive so I have been looking at other options. I can buy a standard cylinder and piston kit for about the same price as a DR177 kit but I am not sure which way to go. I don't want to have to play with it too much to get it running right. I am not after any more power (although it would be nice), and I already have a new standard exhaust so I don't want to replace that. I am after reliability most of all. The scooter will mainly be used around town on short runs. Any advice is greatly appreciated. Cheers Coops.

This oversized Cylinder Assembly may work for you. Keep the crank and exhaust but may need another head.
https://www.scooter-center.com/en/7676515/cylinder-oem-quality-166-cc-oe61mm-3-ports-vespa-px125-px150-gtr125-vnl2t-ts125-vnl3t-sprint150-veloce-vlb1t-0166001

You'd enjoy the extra power of a kit. If I was in your club I'd probably get one just to smoke the other members.

But if you don't think you need a kit, already have a new stock exhaust, want minimal fussing and maximum reliability, it's hard to beat a stock top end.

The DR is a decent upgrade on an otherwise stock bike, so long as you can do the work (right) yourself.

It'll get you a little more top end and a wider power band. It's also the Tuner's Gateway Drug.