The Mishimoto racing thermostat for the 2015+ Subaru WRX helps boost the cooling system's performance in your stock or modified FA20DIT. Compared to a standard thermostat, this product is configured to open at a lower temperature when your engine reaches its ideal running temperatures. This increases the coolant flow and keeps the engine at a cooler temperature, making it ideal for both regular street use and racing. The thermostat is an exact fit to the stock version and will last with the Mishimoto Lifetime Warranty.