Thought you guys might enjoy seeing how this guy upgraded his Dahon Vitesse D7 to a "D18 XT", as seen in this Taiwan foldies forum.
His white Vitesse has Ergon GP1-L grips, '08 XT shifters, DriveLine 53/39 cranks (using an adaptor), Shimano 105 FD, XT RD, '07 LX 11-34T Cassette, and Jagwire cables.
You can see many more pics at the thread (click on the links to open the images).
I love the adaptor they sell there that allows you to hook up a double crank and an FD. Here are some samples:
Which is how they could do this to the Vitesse:
Effectively giving them twice as many gears. Coolness. It is a very popular upgrade for Dahons there.
With the LX cassette and its 9 gears, this Vitesse has 18 speeds to play with.