4-1 Merge Collector 1.5 in Inlet ID 2.5in Out OD

The 4-1 Merge Collector 1.5 in Inlet ID 2.5in Out OD from Vibrant Performance is a premium exhaust header collector designed for high-performance engine builds where four individual runner tubes converge into a single outlet. This component is essential for custom headers, turbo installations, and naturally aspirated engine modifications where scavenging efficiency and exhaust velocity matter. The merge collector bridges the transition from four primary pipes to your exhaust system's downstream components, making it ideal for builders seeking maximum flow characteristics and power gains.

Built from mandrel-bent construction typical of Vibrant Performance's engineering standard, the 4-1 merge collector features a 1.5 inch inlet diameter per runner port and a 2.5 inch outlet outer diameter that accommodates the combined exhaust gas volume. The merge design utilizes proper runner geometry to minimize turbulence and reversion at the junction point, allowing gas molecules from all four cylinders to blend smoothly without creating backpressure waves that impede cylinder evacuation. Weighing just 2.09 lbs, this compact unit (measuring 12.35 inches in length) installs in tight engine bays while maintaining structural rigidity necessary for thermal cycling and vibration resistance.

Engine tuners and fabricators benefit most from this merge collector when building custom exhaust manifolds for street applications, track cars, and forced-induction swaps where OEM exhaust manifolds create restrictions. The 1.5 inch inlet ID specification matches standard 1.5 inch ID header primary tubes, while the 2.5 inch outlet OD accommodates typical 2.5 inch diameter exhaust piping or downpipes used in modern performance builds. Installation requires welding expertise, and compatibility depends on your specific header configuration and exhaust layout; consult technical specifications for your engine platform to confirm proper runner tube sizing and collector mounting provisions before ordering.