Thought I would report a successful custom water cooling setup for two c1's. I used some parts I had lying around from some of my old watercooled PC's.

1 D5 Pump with EK Pump Top
1 560mm Rad GTX560
8 140mm Fans in push-pull

Both C1's in series (refer photo and some screen grabs of the temps which are remarkably even across the two units)

Currently both are overclocked to 262.5 with the default voltage.