Upgrade your race engine's ignition system with the R5671A-9 Racing Spark Plugs (5238) – Set of 8. Designed for high-compression, turbocharged, and high-RPM engines, these plugs provide a strong, consistent spark for maximum combustion efficiency. Featuring a copper core center electrode, the R5671A-9 spark plugs deliver superior heat dissipation, reducing the risk of pre-ignition and detonation in high-performance applications. With a heat range of 9, these plugs are ideal for engines requiring colder spark plugs to handle increased cylinder pressures and extreme temperatures. Trusted by professional racers and performance enthusiasts, these racing spark plugs ensure durability, reliability, and optimized engine performance. Whether you're building a race car, upgrading a high-boost setup, or tuning for peak horsepower, this set of 8 NGK R5671A-9 spark plugs delivers the ignition power you need.