The rev counter parts aren't fitted to the 900cc engine as it works in a different way to the 1108cc sporting engine (2 coil packs meaning its a 2 cylinder rev counter, or something like that). It is possible to get them to work (a friend of mine bought one with a sporting dash and the rev counter worked) but I have no idea how, most people i think settle for not having it working.
I imagine if you buy an after market rev counter you could use the circuitry from that and connect it to the cinq one