Did some research on the net. I figured cooler would be better but it's not. It would best to have a hotter eng (180F) with really good coolant and a cold air supply (RA) into your intake.

It reduces the amount of time your engine fan works to cool the engine thus improves power and fuel economy.

Use less HP all the time with a stock flex fan! IMO

http://www.ls1tech.com/forums/generation-iii-internal-engine/241922-hot-cold-engine-better.html
http://www.evanscooling.com/