Im am turning up to 6330 RPM. Limiter set at 6400 RPM. We stay fairly warm here. Boat also stays inside my building where it is in heat and ac year round. I still drain all water from the motor and turn it over every 4 weeks to keep the springs from having constant pressure on them as far as "winterization" goes. I am thinking i may try the smaller reducer with the larger outlet/inlet from crossover to relief on top of tstat housing first then possibly a 140* tstat. As of right now the engine temp will stay fairly constant around 115-123 running in the summer with the Hardin oil tstat housing with remote filter head and 3" oil cooler.