Industrial Injection 5.9 Cummins Stage 1 Ported & Polished Cylinder Head with Fire Ring Grooves (2003-2007) Upgrade your 5.9L Cummins with the Industrial Injection Stage 1 Ported & Polished Cylinder Head, engineered for daily drivers, towing applications, and performance enthusiasts. This fully assembled cylinder head is CNC ported, fire ring ready, and designed to improve airflow, reliability, and overall engine performance. Built using advanced 5-axis CNC porting technology, every intake and exhaust port is precision-machined and hand-finished to maximize airflow and maintain consistent cylinder-to-cylinder performance. The result is improved horsepower, torque, throttle response, and reduced cylinder pressures. Each cylinder head comes complete with premium stainless steel nitride-coated valves, high-strength alloy valve guides, oversized high-temperature valve seats, and 95lb performance valve springs manufactured in the USA for increased durability. To improve long-term reliability, the head features drilled and tapped steel coolant freeze plugs that eliminate the common failure points found in factory press-in plugs. Radius-cut fire ring grooves are machined into the head to work with a fire ring head gasket, helping reduce the risk of head gasket failure in high-performance applications. Features: Fully CNC ported and hand-blended cylinder head Radius-cut fire ring grooves for improved head gasket sealing Performance stainless steel nitride-coated valves High-strength hardened alloy valve guides Premium oversized high-temperature valve seats Drilled and tapped steel coolant freeze plugs 95lb USA-made performance valve springs Complete and ready to install Benefits: Improved airflow and engine efficiency Increased horsepower and torque potential Enhanced durability for towing and performance use Better valve train stability at higher RPM Reduced risk of dropped valve seats and freeze plug failures Designed for long-lasting reliability and daily drivability Note: Fire Ring Head Gasket sold separately.
