I wouldn't worry about the 22 cfm spec, I think that might just be the cfm used for the 1/2 second that you are breaking the bolt free, or the last 1/2 second of tightening it. I think the important spec is the avg. cfm. How often are you going to use it? Occasionally, or all day/everyday? I've got the 2131QT
http://www.sears.com/sr/javasr/produ...tive+Air+Tools that I run off a Dewalt framing compressor that's only 4 gal, but has 4.5 cfm @ 100psi. The compressor has no problem keeping up, but it will run alot since it's only a 4 gal tank. I only use the wrench occassionally, so that doesn't bother me, I just put the compressor around the corner and run a long hose, so I don't go crazy from the noise. Hope this helps.
Cameron