T5 exhaust on P2

How do fellas, while perusing the SIP vespa catalogue i came across a tip for basically, sticking a T5(standard) exhaust onto a P2 by just cutting off and welding on the appropriate manifold connection to fit the pipe to the bike. Has anyone actually tried this and if so what was gained from doing it? If there was any point in doing it wouldn’t it be more effective than to do it with a sito plus or does basic build quality have a lot to do with this?

Cos a Sito+ will rot quicker than an unpainted Vespa in the north of Scotland.[:D]

Why not just by a P2 exhaust!