OEM fans are popular and that's a good thing - cheaper in the wrecking yard (maybe) and they move lotsa air. The factories have a stake in keeping cars away from warranty issues, so they pretty much science it out. Lots of folks buy the smaller aftermarket fans. Those are good fans but most inexpensive ones are not capable of pull enough air through a core. The best combination I have found for cooling with electric fans is a dual core aluminum radiator and hot (195 F ish) water. The dual core aluminum units allow more air through and have larger diameter cores with more surface area. The dual Camaro OEM types fans on my car are great - drive it anywhere. The dual 12" eBay units on the Mustang are good for racing but you would not want to try driving it on the street. That's not how I set up the system anyway.
1967 Falcon 4 door 351C-4V
1970 Mustang 351C-2V
http://raceabilene.com/kelly/hotrod
Owner built, owner abused.
