Clutch fan vs derale single 2400cfm fan

What blows me away is even with dual fans you can't get the cfm higher than 2500. I even looked at the HHR fans that people mentioned in past posts but that doesn't put much out either
There are many electric fans on the market well above 2500CFM. They ain't cheap. I agree with the clutch fan though as long as you have the room.