It's all about your combination. New cars have electric fans but their job is to cool at low speeds or stop & go traffic. All aftermarket manufacturers claim a CFM but that's an unrestricted flow rating. Look at it this way. If an electric fan pulls X CFM, that flow would also be equal to the flow at X MPH. Once you exceed that X MPH, the constant speed fan is useless. Now the flow needed has to be greater than the restriction of the fan body and the shroud.
I started with thin flat shroud that had about 1-2 inches between the shroud and the radiator core which was too close. The shroud had some openings with small rubber flaps to allow excess air to pass but were to small to make a difference. I had two 10" fans (22x18" radiator) that were the highest advertised CFM I could find. Obviously, at speed the combination became a big restriction. All the air had to funnel its way through the two 10" holes with fans in them and with only 1-2 inches clearance between the shroud and core. I finally got it right, lesson learned. Would that setup work on a different car, absolutly.
Sorry about the long winded post. Congratulations to the guys that got it right the first time and good luck to you.