I put a SPAL fan on my ex girlfriend's Camaro. I used to think SPAL was the best, but I was wrong. The car immediately started overheating if it sat still too long. Those SPAL fans don't put out anywhere near the CFM advertised, and certainly no where near as many CFMs as the stock one. The first fan I got seized within 4 weeks. We got a new one under warranty, and the second one seized within a week. I put a $15 flex fan on the car from the autoparts store, and it never overheated again. If your car is running hot, and you want to get it to cool down, the best option is to put a factory replacement electric fan off a 95 Ford Taurus 3.8. The stock fan on that car pushes over 4000 CFMs. You can find them on ebay for about $80. It's by far the best bang for the buck I've ever seen.
Kurt