Hey MrGreenFingaz
Take a look at www.plantlightinghydroponics.com they have the fans you are looking for.In that small of space a 4"vortex can fan would do it for you.
The 4"fan has a 172 cfms and 49 db noise level,the 6"fan has a 449 cfms and the same 49 db noise level too.The 4" fan is 9.5" H and 8.5' wide,the 6" fan is 13.0"H and 10.5" wide.The 4" fan is about $109.90 and the 6" is about $149.90 plus s&h .I have the same problem with MS panit too.
Have a Good One. Peace