Lower your coolant temperature in your motor and you will lower the temperature of everything under the hood. That, in turn, should make more power...cooler, denser air makes better power. Or, think of it this way; you will heat up the air less on the way to the combustion chamber with the hot engine parts. This on a Focus pays additional benefits, you will be less likely to have the ignition advance reduced by the engine management because of high air intake temperatures.

For years, the automotive industry used 180 degree thermostats as standard equipment, so do not worry about it being too cold in most environments.