Has anyone shopped for an air compressor lately? It's amazing how far retailers will go in providing exaggerated/skewd/completely misleading info on these things. Due to this, I have a question: -Is there a simple formula for working with cubic feet per minute (cfm) and PSI? Ex: If you know that a certain compressor delivers 25 cfm @ 175 psi, would it be possible to determine what the cfm would be @ 90 psi? ...or are there other factors involved which prevent such a simple formula? Thank you.