4-1 S.S Merge Collector (1-7/8in Inlet ID 2.5in

The 4-1 S.S Merge Collector from Vibrant Performance is a premium stainless steel exhaust manifold designed for builders seeking to consolidate four individual cylinder runners into a single merged primary tube. Purpose-built for street, strip, and track applications, this collector bridges the gap between high-revving performance engines and efficient exhaust scavenging. If you're upgrading a carbureted or fuel-injected V4 engine platform or fabricating a custom build, this merge collector eliminates the restrictive stock manifold design while maintaining structural integrity and thermal efficiency across the powerband.

Constructed from mandrel-bent stainless steel tubing, the 4-1 design features 1-7/8-inch inlet diameter per runner, engineered to promote exhaust gas velocity and scavenging efficiency at mid to high RPM ranges. The merge collector consolidates these four pipes into a 2.5-inch outlet diameter, optimizing pipe diameter transition to reduce turbulence and backpressure while supporting direct bolt-on or custom piping configurations. Stainless steel construction resists thermal corrosion and oxidation, delivering durability under sustained heat cycles that would compromise mild steel alternatives. Weighing just 3.2 pounds, this compact design (12.1 inches in length) fits tightly in modern engine bay constraints without sacrificing strength or flow capacity.

The 4-1 S.S Merge Collector suits domestic and import V4 platforms, particularly fuel-injected four-cylinder builds targeting 5,000+ RPM sustained operation. Installation typically requires custom downpipe routing and O2 sensor bung verification; confirm your engine's specific flange pattern before ordering. Pairing this collector with a tuned exhaust system, optimized fuel mapping, and proper ignition timing yields measurable gains in mid-range torque and peak horsepower while reducing exhaust manifold heat soak. Mechanics and weekend fabricators value Vibrant Performance's quality for its weld integrity, dimensional accuracy, and long-term thermal stability in high-output street and racing engines.