I,ve just fitted an 220mm organic AP CP2000-8 clutch to the S1, seems to be handling the power at the moment and drives fine. Did need to change the pedal and quadrant (the AP site gives full details and part numbers), but that was easy enough and isn't always needed, fit it first and see how it feels, if the bit is to low down or you can't get t the gears then change the pedal etc

I wouldn't go for a cheaper version of the organic clutch as they apparently aren't much better than standard. stick with AP, you'll feel the quality