My brother plugs the bypass and runs no stat on all his race cars. He has never had a problem. But they don't get driven on the street either. On my car I have run it with a 160 and 180 stat and also plugged the bypass hole and ran it with no thermostat. It made no difference in the temp it ran in the hot summer 90 degree plus days.

Even with the bypass plugged and no stat on hot summer days it will warm up at what seems normal time to me. It will run around 180 to 190 with or without the stat. Only time it will creep up over 190 is on very hot days sitting in traffic for more then about 15 minutes and then I just turn on my electric backup fan which keeps it around 185 to 190. But on hot summer days I notice no difference if I run a stat or don't run a stat and plug the bypass so all the coolant goes through the rad. Ron