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Hedman Hedders 21142 Exhaust Header Reducer 3 Inch to 2.5 Inch with O2 Sensor Bung

Manufacturer

Hedman Hedders

<h3>Hedman Hedders: Over 70 Years of American-Made Exhaust Performance</h3><p>Few names carry as much weight in the hot rod and performance world as <strong>Hedman Hedders</strong>. Founded in 1954 by Bob Hedman, the company holds a unique distinction: <a href="/309-hedman-hedders-exhaust-header-5848">Hedman was the world's first mass producer of exhaust headers</a>, born from a grassroots passion for drag racing and engine performance. What started as Bob selling hand-welded exhaust tubes to fellow racers eventually grew into one of the most recognized brands in American performance manufacturing — and every header is still made in the USA.</p><p>Bob Hedman's origin story is the stuff of hot rod legend. As a teenager, he swapped a flathead V-8 into a Model A and never looked back. His early curiosity about exhaust flow led him to purchase the Equaflow exhaust business in 1954, rename it Hedman Muffler and Manufacturing, and pivot entirely to building &quot;hedders&quot; — the intentional misspelling a clever way to brand the product as uniquely his own. Demand from the drag racing community exploded almost immediately, and the company name was soon changed to Hedman Hedders to reflect what the brand had truly become.</p><h3>What Makes Hedman Headers Stand Apart</h3><p><a href="/309-hedman-hedders-exhaust-header-5848">Hedman exhaust headers</a> are engineered for performance, restoration, and engine-swap applications across GM, Ford, and MOPAR platforms. The lineup spans long-tube, mid-length, and shorty configurations, with designs tailored for everything from classic muscle cars and C10 pickups to modern LS swap builds. Headers are constructed from mandrel-bent primary tubing with laser-cut flanges, ensuring consistent fitment and leak-free performance — hallmarks of a brand that has refined its craft over seven decades.</p><p>One of Hedman's most enduring contributions to the industry is the HTC (High Temperature Coating) ceramic-metallic finish, a technology that <strong>Bob Hedman himself developed</strong> and that remains widely used by exhaust manufacturers to this day. Available in polished silver, satin black (Black-MAXX), and stainless variants, these coatings resist corrosion and withstand extreme heat, while also carrying their own multi-year factory warranty on top of Hedman's standard limited lifetime header warranty.</p><h3>A Complete Exhaust Ecosystem</h3><p>Beyond their flagship headers, Hedman supports a full exhaust installation ecosystem. Proper header installation often requires connecting the collector to the downstream exhaust system, which is where <a href="/309-hedman-hedders-exhaust-header-reducer-16774">Hedman exhaust header reducers</a> come in. Available in ball-and-socket and 3-bolt flange styles, these reducers are sold as matched pairs with all necessary hardware, making the transition from header collector to exhaust pipe clean and secure.</p><p>Sealing the system correctly is equally important. <a href="/309-hedman-hedders-exhaust-flange-5824">Hedman exhaust flanges</a> and gasket hardware are purpose-built to mate with Hedman header collectors, ensuring tight, leak-free joints that hold up under the thermal cycling of performance driving. For vehicles equipped with factory emissions systems, Hedman also offers parts that support <a href="/309-hedman-hedders-secondary-air-injection-check-valve-22222">secondary air injection</a> compatibility — many Hedman header configurations are offered with A.I.R. provisions built in, and associated check valve components help maintain emissions compliance on applicable builds.</p><h3>Built for GM, Ford, and MOPAR Enthusiasts</h3><p>Whether you're building a period-correct street machine, swapping in a modern LS engine, or extracting more power from a stock small-block, Hedman Hedders has a solution engineered specifically for your combination. Their engineering team continuously updates fitment data to accommodate new suspension components, steering upgrades, and chassis configurations — so builders get headers designed for real-world clearance, not just theoretical fit. For classic car restorers and serious performance builders alike, Hedman remains the standard by which American exhaust headers are measured.</p>

Part Number

21142
07/21/2036 11:37 PM
Sale Price

$22.08

In Stock (10+)

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Usually delivered within 2 days

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No Hassle Returns

No Hassle Returns

Live-in-stock inventory

Live-in-stock inventory

Fitment guaranteed

Fitment guaranteed

Product Details

The Hedman Hedders 21142 is a 3-bolt gasket-style header reducer designed to connect a 3-inch header collector to a 2.5-inch exhaust system. This reducer features an integrated 18mm oxygen sensor bung, allowing you to monitor exhaust gases for proper engine tuning and emissions compliance.

Key Features:

  • 3-inch collector size with 3-bolt triangular flange design
  • Reduces to 2.5-inch exhaust system diameter
  • Includes 18mm threaded O2 sensor bung
  • Constructed from durable mild steel material
  • 0.3125-inch flange thickness for strength and durability
  • Made in the USA

Complete Installation Kit:

Each kit includes one mild-steel reducer with gasket, bolts, nuts, and washers for a complete installation. Simply weld the reducer to your exhaust system, then bolt up your headers for a secure, leak-free connection.

This reducer is ideal for custom exhaust builds where you need to adapt larger header collectors to smaller diameter exhaust piping while maintaining the ability to install an oxygen sensor for proper air-fuel ratio monitoring.

Products specifications

Bolts/Studs Included

Yes

Collector Attachment

3-bolt flange

Oxygen Sensor Bung Included

Yes

Quantity

Sold individually.

Reducer Finish

Painted

Reducer Material

Steel

Reducer Outlet Diameter

2.5 in.

fast ordering pics helped.

I was updated when my package was shipped and given a time and date that it should arrive.

As advertised.

Easy checkout! So glad that THMotorsports gives the option for PayPal checkout... makes the process much more hassle-free.

good

It was quick n easy

Received just what I ordered in just a few days. I can't review the tires yet because I haven't put them on.

Looks absolutely great on truck- thanx

Happy with my purchase and the time it took to get it to me was was very reasonable, I would order through autoplicotiy again

good price

Was a great price and in stock. Hope I get it fast for the cruizin' coming up soon.If so I will be hooked

very good prices. good service.I am a future customer.thanks.

I placed an order on Monday & received product on Saturday. I am very pleased with the turn around time & the price. They had the best price on the internet that I found and they were helpful to work with.

Timing gearset arrived in under 48 hrs! Gears look well made. Can't wait to get them on my car. Thanks for the great service!

Order shipped without delay and Autoplicity had the best price. One of the problems was I did not get order confirmation email or could not get the order details in my account. Unfortunately, I registered after placing the order because the process was not that straight forward. They could not get my order details into the account. The tracking email was received little late. I wish they improve the system to add orders to the account and display the order progress.

Great Products, Very Cheap, Fast Shipping. Will be a returning Customer. A+++

Very good product, the green caliper paint is great.

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