uhhh, not sure where your at, but down here in Texas a lower degree thermostat most definitely reduces the operating temperature. If your cooling system is up to par, the radiator has plenty of time to cool off between cycles when using a lower thermostat.
FYI One of the most common GM EFI tricks is to run a lower thermostat to keep the engine running cooler so that the computer can run a more aggressive timing curve.
