3-Bolt Exhaust Flange Collector w/ O2 Bung, 3.5/3.0-in

• Traditional 3-bolt header flange bolt pattern for 3.50-inch header collectors
• 3.0-inch outlet features slip fit/weldable connection to your existing or new exhaust tubing
• Manufactured from mild steel materials with a raw finish ready for coating
• Oxygen sensor bung welded into tube with O2 sensor plug included
• Sold as a pair and includes mounting hardware and 3-bolt flange gaskets

Add Oxygen Sensor Bungs to Your Exhaust with Standard 3-Bolt Header Flanges

Many headers today still use the standard 3-bolt header flange connection at the header collector. It is a simple and easy way to connect your exhaust system to your tubular headers. While some headers include a mating 3-bolt flange “starter tube” in their header kit, not all do. On top of that, older headers that were not designed around the use of aftermarket fuel injection systems, wideband oxygen sensor air/fuel gauges, and even the use of wideband O2 sensors as part of dyno tuning, do not have an easy way to install the O2 sensor without having to remove the header, drill a hole, and weld in an oxygen sensor bung. If you need to add an O2 sensor bung to your header our 3-bolt header flange with integrated O2 sensor bung is what you need!

Made from mild steel, our 3.50-inch diameter 3-bolt exhaust flange features a reduced 3.0-inch outlet connection ready to weld or clamp to your exhaust or turbo system hot side. The oxygen sensor bung  comes pre-installed, saving you time and frustration. The oxygen sensor bung can be used for your EFI system’s wideband oxygen sensor, or the sensor that is included in an air/fuel ratio gauge. As mentioned above, many dyno tuners run a wideband oxygen sensor for dyno tuning as well, so having the O2 sensor bung ready at hand makes things easy. An O2 sensor plug is included for each O2 sensor bung when the bung is not in use or not required, so there’s no need to screw in an old spark plug! Just thread in the included oxygen sensor plug. See our full line of header reducers if you’re looking for additional inlet/outlet sizes.