A little late on this comment, but I will throw in my 200,000 miles of advice. The lower temp thermostat just delays the inevitable. I have tried every likely combination, from no thermostat (worked fair in the summer heat in deep South Texas, but was a disaster in the winter driving through Arkansas), a gutted thermostat, 160, 170 and 180 degree Motorad and Stant units. Never tried a 190 for obvious reasons. I am currently using a stainless (trying to eliminate as much copper/brass as possible to protect my aluminum radiator, manifold and heads) Motorad 180 unit. I have found the obvious; the engine warms up faster with the 180 and sees the same top temps. Also, I have found that the engine actually runs it’s absolute best at 220-230 degrees indicated, both on the street and on a chassis Dyno. 55 mph cruise gets about 190 indicated, 70 mph cruise about 210-220, depending on ambient conditions. Using some type of front spoiler or air dam brings the cruise temp down by spoiling off the high pressure area under the front of the car allowing better radiator airflow. I have used one in the past, but not now. I also use a full radiator shroud, which really helps. The opening temp of the thermostat is far less relevant than good airflow.