How much of a temp. diff would there be if i changed over to a 160 degree thermostat? I have a 170 degree unit now along with a 17" flex fan and a short fan spacer and no shroud and a 3 core rad. in front of a 396 in a 68 Camaro. I just changed to a taller spacer and am buying a 19" flex fan. Will the lower temp thermostat make much of a difference?