You might want to consider some typhoon's insted, if you need more air pressure 
I heard about them, but I couldn't source them easily.
Noctua are 1200 rpm ; are the Typhoons really more effective ?
The Typhoons and Noctuas are better for high pressure applications, like pushing/pulling through mesh or a radiator. The Typhoons @ 1850rpm are actually quieter than my Noctua 1500rpm fans, and perform a bit better on my radiators.