Mishimoto MMTS-350Z-03L Nissan 350Z Racing Thermostat, 2003-2006 Fits the 20032006 Nissan 350Z Activates at lower temperature so coolant flows through system earlier Allows for cooler engine temperatures OEM Activation: 169.7F, 76.5C / Mishimoto Activation: 154.4F, 68C Mishimoto Lifetime Warranty