Performance Thermostat, 68C/155FThe Mishimoto racing thermostat for the Subaru WRX 2001 2014 STI 2001 2021 will promote greater cooling efficiency throughout your engine. The Mishimoto racing thermostat will significantly lower high engine temperature produced by modified and upgraded turbo applications. Once the engine is fully warmed up, the Mishimoto racing thermostat will open up at a lower temperature than standard thermostats, allowing the coolant to flow through the engine