Muzzy sales rep I spoke with claimed a 30-40% increase in flow over typical stock fan. In hot weather and stop and go traffic, my bike runs the fan what seems to me an excessive amount, so a more efficient fan seemed worth a try. In fact, at higher temps when the bike isn't moving, the coolant system does not seem capable of dropping temperature to a point where the fan will cycle off. In my experience, this is unusual with an electric fan... Anyway, a $40 accessory seemed worth a try.