Performance Thermostat, 74C/165FThe Mishimoto BMW Racing Thermostat fits all N52, N54, and N55 engines. It will promote greater cooling efficiency throughout your engine. Mishimoto racing thermostats will significantly lower high engine temperature produced by modified and upgraded N52, N54 and N55 engines. Once the engine is fully warmed up the Mishimoto Racing Thermostat will open up at a lower temperature than the stock thermostat, allowing the coolant to flow through the engine