We have a 4 cfm DigiQ and live in Denver area, mile high city. We just smoked 4 butts and the 4cfm fan didn't seem to hold the temp. for 4 butts as well as it did for 3 or less at a time. We are thinking we may need a 10cfm but don't want to go to the expense right now. Any ideas of other fans that could work or how to improvise this one to work?