The Mishimoto racing thermostat for the 03-06 Mercedes Benz E55 AMG will promote greater cooling efficiency in your stock or modified M113 5.4L Supercharged engine. Once the engine is fully warmed up, Mishimoto's E55 AMG racing thermostat will open at a lower temperature than standard thermostats. This allows coolant to flow through the engine sooner, which reduces and maintains cooler engine temperatures. The Mishimoto 03-06 E55 AMG racing thermostat is the perfect addition to your street or track AMG and is a direct replacement for the stock thermostat. This thermostat includes the signature Mishimoto Lifetime Warranty.