i got told by some guys at autobarn today, cos they supply them... that they have used this on a race car to good effect, also a road car had one put on but i dunno how that one went
from what davies craig have sed, the pumps stops heat soak after the engine has shut down, by keep pumping the water so it cools down more evenly or soemthing to that effect
both the fan and pump will reduce lag on the pulleys giving more response and acceleration. also using light weight pulleys and undersizing them(?) will also help this to become more effective