I found this company while looking at aftermarket fans. They might be a good company to contact when looking for one. The CFM rating on them are very high! If more air going through the radiator is needed, one of these should do it. I don't think it would be a direct plug & play with the system though. Could be a viable option.
http://www.electricfanengineering.com/index.htm
http://www.electricfanengineering.com/index.htm
