A 5 hp two stage will deliver 15-17 cfm, 7.5 hp is in the 20 range.? My dryer is a Hankison Hi Temp refrigerated.? Whether you need the higher input temp depends on how large your tank is and how much air you need.?? I got my compressor and dryer used so took what I could find.? You have to be careful when buying a dryer used.? If they have been ridden hard and put away wet they are not repairable for a reasonable cost.? Dave