3in To 2-1/2in Collector w/O2 Sensor Bung 3 Bolt

The 3in To 2-1/2in Collector w/O2 Sensor Bung 3 Bolt from Hedman is a critical transition piece for custom exhaust manifold systems designed to step down larger primary tubes into a single collector neck. This reducer collar serves as the bridge between your primary runners and the exhaust piping downstream, making it essential for builders transitioning from multi-tube manifold designs to single-outlet configurations. Whether you're fabricating a performance exhaust system, upgrading to a turbo setup, or fine-tuning a street engine build, this collector provides the proper step-down ratio while maintaining structural integrity under sustained exhaust gas velocity and thermal cycling.

The 3-bolt flange design ensures a tight, repeatable seal with your manifold or primary tube assembly, eliminating exhaust leaks that rob horsepower and create noise. The integrated O2 sensor bung allows direct mounting of oxygen sensors into the collector body itself, a critical advantage for tuning and emissions compliance—you'll avoid costly adapter fittings and get cleaner, more responsive sensor readings without lag. The stepped interior geometry minimizes turbulence during the transition, preserving exhaust scavenging characteristics that maximize cylinder evacuation and improve overall engine efficiency. Hedman's proven cast construction handles sustained high-temperature exhaust flow while resisting cracking under thermal stress.

This collector suits street performance builds, turbo manifold applications, and custom engine swaps where you need a reliable transition from 3-inch primary tubes to 2.5-inch downstream piping. The O2 sensor bung is indispensable if you're running a tunable ECU or standalone engine management system and need sensor placement before your catalytic converter or resonator. Installation is straightforward—bolt it to your manifold or header flange, weld or clamp the outlet to your piping, and thread your O2 sensor directly into the bung. This compact design weighs only 1.52 lbs, keeping underhood mass minimal while delivering professional-grade durability that withstands years of track use and street driving alike.