Hi Deandy, I think it boils down to what look you like. Some like the twin pipes and some a single. I would be very happy with either the Leo Vince or the single Exan. Performance wise and weight wise much better than stock. I can't comment on any other pipes as these are the only 2 I've used and owned.
You are very lucky to live in Switserland with its fabulous roads through the mountains. Please show us some pictures.

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2010 XT660Z Blue, Exan can, UFO high front fender, SW Motech baseplate, heated grips, 12v point, Kevs Fuel & O2 mod, DNA Stage 2 Filter and cover, Givi tall screen, Mefo mfe 99s, Kevs throttle mod, TT high seat and 'compass'