There's a fan called the Scythe Ultra Kaze that runs at 3000 RPM, pushes a ton of air and is slightly quieter, but it only works if u have the non-autotune S9 and can downclock the frequency a bit.
If I may, the Ultra Kaze is good - but - Enermax Twister Storm is better @ 3500 RPM for +150 CFM / +11 Static Pressure. It's working great on my Spondoolies SP20E. I've also, in order, a possible new king of the road (non delta / low noise), the Silverstone FHP141-VF @ 2000 RPM for +170 CFM. It's a 140mm mounting as a 120mm, one catch - the Static Pressure seems to be around 4...