Colder Spark Plug - Roush Number: 401546

Prevent pre-ignition and detonation of the fuel due to the higher cylinder temperatures found in supercharged engines with these colder spark plugs These ROUSH Performance Colder Plugs are one heat range colder than the stock Mustang plugs and are designed specifically to handle the high boost pressure and air flow into the engine These plugs feature a 0.045 inch gap Pre-ignition is typically caused by many factors, such as an overheated spark plug tip which acts like a glow plug to ignite the charge. This puts a tremendous load on the engine and adds considerable heat, a recipe for serious damage. Sold individually.