Welcome on board Bernard!!! As far as I knew the XT660 engine is made in Italy as Yamaha purchased the Minarelli factory and the bike is also assembled in Italy, you can see loads of European bits (Acerbis, Brembo). The MT03 is still popular here and as you mention they share loads of bits with the XT660 so you will loads of useful info on this site. Enjoy!!

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(Now sold on, sob) 2011 Blue XT660X with gold wheels, was 26,500 km.
Engine mods: K&N Stage 1 filter, DNA Stage 2 filter, snorkel removed, Kev fuel mod fitted.
Plus: smoked Puig screen, Yam aluminium sump guard, Yamaha / Acerbis handguards, Givi Trekker aluminium side cases, Leo Vince X3 cans plus Kev front fork mod and Fender Xtender. Just fitted Michelin Road Pilot 3 tyres.

SOLD the XTX for a Super Ten 1200. And just bought a Raptor 700 so staying on here for some tips....