If you're car cooling system (including the fans) are working properly then you should not need another extra fan in front of the radiator. If you still want more cooling power from the fan, rather than having another extra fan, I'd rather find a compatible fan with more blades if available, or maybe change the motor fan with even faster/stronger one. Another option is to use better radiator.

Btw do you actually have overheating problem? Or your aircon is not cold enough? Just want to understand the exact reason why you're asking to add extra fan. Coz if you're having one of these problems or both, then extrafan is actually not the real solution.