IMO, running a cooler thermostat to keep a engine from overheating is an OLD WIVES TALE! The thermostat sets the minimum temperature and once it opens it also restricts the water flow through the engine. The engine / oil are designed to run at ~ 200-210 degrees, the faster it gets there the better for the engine. Its especially a bad idea in a cold climate. It might produce a small amount of increased power at the expense on increased engine ware rate. For the money, the larger transmission cooler is a better investment.