Modern Vespa

How do I get the exhaust studs off when the 10mm socket has rounded off the nuts? I've tried the 3/8 socket to a similar effect.

a fluted extractor/remover socket works well, but you might not have enough room to operate up under there depending on the model. you can buy a few and have a go, you'll know straight away if it's a workable situation and if not you can just return what you don't use.

I have a set of these universal/spline drive sockets that work well. they absolutely mangle fasteners, but they can get the job done. here's a link to them at summit racing, so you might be able to find something similar on amazon or at a UK supplier. powerbuilt universal socket set

no matter what you use, get some penetrant up on there to soak before having another run at it.

If you loosen one side, there will be play so you can likely loosen the other side too. One thing you can do is put two nuts on the end of the stud, lock them in place and back the stud out of the head.