I was reading this thread and I though I could offer some information that I received from a MINI factory engineering person. Apparently overdriving the blower is leading to poor water-pump operation. Not because the pump is weak. Once the pump speed surpasses the design limit, it causes cavitation. Once you have cavitation the water will not flow. Fortunately this only happens at the highest rpm limits. A daily driver probably won't encounter this problem as the high revs are not sustained for long periods of time. On the track is another story...
The stock blower has no ceramic treatment like the cooper-works blower. The Ceramic rotors are a very tight fit. The clearance between the rotor and blower housing is very close. They can do this with the ceramic coatings as the rotors will not grow under full duty. The stock superchargers will fail in time. It's just a matter of time and excessive heat cycles before the rotors start to gall and fatigue.
Hope this helps
