A Guide to Open Headers: Your Questions Answered

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open headers

When a vehicle runs only via the exhaust headers alone, this is known as an “open headers.” It means that a car runs without the main parts of the exhaust system, such as the muffler, catalytic converter, resonator, and exhaust pipe—the car’s emissions blow straight outside through the exhaust headers only! Holy Moly! Can you imagine how loud that is?

Headers are typically among the most straightforward bolt-on equipment for increasing engine performance. The purpose of headers is to assist the engine in expelling exhaust gases from the cylinders.

While depending on the engine displacement, open headers may significantly enhance your car’s horsepower output. The larger the engine block, the higher the horsepower it can produce. That also means a deafeningly loud and mean “vroom!” noise from the engine.

We’re about to take a deeper look into open headers in this article. The fundamentals, such as what open headers are, their advantages and drawbacks—particularly in compliance with applicable traffic rules and regulations.

So if you’re serious about experimenting with your car, you’re in the right place to learn everything you need to know about open headers.

What are Open Headers?

With open headers, you may operate your vehicle without a muffler, exhaust pipe, and catalytic converters. Gases escape straight into the air through the headers. Like drag cars, open headers are used chiefly for sound and maximum performance. It is substantially less constraining than the stock car configuration.

Larger engines such as a V6, V8, and V12 may produce a pretty intense sound and generate spewing flames when revving to higher rpm’s or approaching the RPM redline. There is none more audacious than this. Open headers are powerful and awesome when appropriately handled – imagine driving on a drag strip’s track, isn’t that cool? However, driving a car with open headers on a public street is a sure way to get into trouble with the authority.

Headers vs. Manifolds

Are headers different from Exhaust Manifold? Yes, but they perform almost the same function; the difference is in the manufacturing process. The distinction between the two is that an exhaust manifold comprises a solid cast iron design that spans all the engine cylinders. In contrast, a header consists of separate steel pipes for every exhaust outlet welded together and meets at the collector to gather exhaust gases.

exhaust header

The power stroke is when your car’s engine generates all of its power. The fuel in the cylinder ignites and expands throughout this stroke, generating power. After the fumes escape the cylinder, they travel into the exhaust manifold and then into a single pipe leading to the catalytic converter.

The header contributes to the elimination of manifold backpressure. Thus, rather than a single manifold used by all the engine’s cylinders, every cylinder has its own exhaust pipe, which connects to a bigger pipe known as the collector.

Car Tuning

To correctly run open headers and add horsepower, tuning is a must. Because your vehicle’s fuel and air ratio are dramatically altered, you have to remember how that influences other parts, such as O2 sensors.

Through tuning, you can tell the electronics in your car to deliver more fuel and adjust the fuel/air ratio. This means that your engine will use more fuel and air during each combustion cycle. As a result, more power is generated.

exhaust manifolds

Additionally, extra components outside the fuel/air ratio may be tuned. Consider eliminating the engine’s rpm limit and adjusting the motor’s torque map, among other things. Getting a tune at a nearby tune shop would be a breeze.

Basic tunings are inexpensive, ranging from $200 for a simple tune-up to $500 for a complete tuning. If you like to reattach the exhaust pipe, tuning is unnecessary.

Horsepower Improvement

Open headers will undoubtedly increase your car’s horsepower. This is achievable because exhaust gasses flow freely and provide many gasses thru the pipes. This change in gas flow allows the engine to pull in more air and generate much larger combustion for extra power.

It is likely to add 30-50hp to your vehicle based on the headers you have fitted. The engine’s displacement also serves as a significant influence in determining whether or not this upgrade will assist you in producing some pretty figures.

Because you’re adding more air to the engine, you will require a greater intake. In my perspective, the best component to add is a cooler air inlet. After that, you can upgrade to larger injectors and a more powerful fuel pump.

Pairing open headers with other modifications such as a cold air intake and tuning may result in an additional 100 horsepower or above. Of course, an extra 100 horsepower is under ideal conditions, dependent on many circumstances, including your budget. 

Loud Noise

Due to the increased combustion power and lack of sound reduction features (such as mufflers), you can anticipate that open headers will create significantly more sound – up to 5 times more. Louder than straight pipes and muffler delete, evidently unsuitable for public street driving.

Laws and Trouble with the Authority

Automobiles with open headers aren’t permitted on public roads – primarily due to the excessive noise and toxic exhaust emissions. If you drive a car with open headers in public, you will definitely find trouble with the authorities.

header pipes

It’s impossible to conceal your open headers. Traffic officers are sure to notice you and issue two fines against you, one for causing a disturbance and another for the toxic emissions.

Additionally, your open headers are sure to fail any standard emissions tests. Reinstall your exhaust before hitting the public roads on your way to the emissions test!

Below are some of the laws you might violate when running open headers on public roads.

Vehicular Noise Standards

The primary disadvantage of open headers is their ear-shattering loudness, particularly at high throttle. Each zone has enacted some noise regulation for vehicles. Even a 4-banger car with open headers can be noisier than most cars.

Vehicular Emission Standards

Cars are a significant cause of air pollution. For fuel quality standards and exhaust emissions for all vehicles, laws are in place to regulate motor vehicle emissions and protect public safety. 

Emission Exemptions

Only a few vehicles with open headers can circumvent local emissions regulations and noise laws, but those few that can go are usually oversized trucks. Some local governments did not require automakers to put catalytic converters on all of their vehicles back in the day. Therefore, if your vehicle was produced in or around the 70s, you can lawfully drive open headers on the streets. As long as your car was not originally equipped with a catalytic converter (in other words, if it’s still in “stock” mode). 

Noise Exemptions

Noise exemptions are not always rigid; some areas use a rolling scale based on the car’s classification and manufacture year. Trucks with a total weight of 10,000lbs or more that were manufactured in the 60s and 70s are not accountable to any noise laws. Many places use similar rules, including several US states, so review your local regulations to determine which ones apply to you.

Exhaust Cut-Outs

Vehicle emission laws expressly prohibit the installation of any device that bypasses the muffler or catalytic converter by a car owner or repair shop. Assuming your headers do not fall in line with the stock or factory exhaust, there’s no reason you can’t run a second outlet from the header collector to the catalytic converters. Doing this creates an opening at one point of your headers, which must be filled. What you choose to install in that opening is entirely up to you.

Spark Arrestors

Don’t assume you can run an open header on an off-road truck because you pass the emission exception law or intend to go off-roading and run it in the mountains. Even though the engine in your truck may be quieter than the decibel limit set by your region, you’re still required to have a spark arrestor to run it off-road. Such devices are critical in forested locations, where the flames erupting from the headers of your truck might quickly start a fire.

Impact on the Engine

Open headers cannot create engine harm if you have tuned and balanced the air/fuel ratio. However, open headers may substantially alter the air/fuel ratio when run untuned, bringing and mixing more oxygen into the combustion cycle in the combustion chamber.

Increased oxygen in the combustion chamber might make a dangerous impact on your car’s engine. It can cause your engine to run lean – which is harmful since it is likely to overheat.

If your vehicle has an older carbureted engine, you don’t need tuning for open headers. Rather than tuning, you should adjust the carburetor’s setting to achieve a proper air/fuel ratio balance.


Despite having open headers on your adored ride to look badass and sound tough, it’s not advisable, especially if you intend to show off by running it on public streets. Besides, being a responsible car owner is essential, and if you’re not using your car on the drag strip, there’s no viable reason to have open headers. 

However, If you want to deploy your car on a race track, this modification will improve your ride by adding significant horsepower. It will also satisfy your craving for speed and good sound. If you’re curious about your car’s capacity without the weight and hindrance of having an exhaust, you should try running it with open headers and observe the difference. 

It’s a lot of fun, especially when running it with your squad. After the experience and a long run, you can reinstall your entire exhaust system and run it legally on the streets!


Can You Drive Your Car With Open Headers?

Open headers are used exclusively on the race track where it is permissible. Avoid running open headers in your everyday driving, particularly on-street use. The obnoxious noise and excessive emissions will undoubtedly result in a penalty with the authorities and, in some instances, issues with your neighbors.

Can You Pass Emission Tests With Open Headers?

Any car with open headers is guaranteed to flunk a standard emissions test. Emission test centers don’t care about your open headers and top engine performance. Rebuild and reinstall your exhaust system before hitting emission test centers.

Why are Open Headers Illegal?

Open headers are illegal almost everywhere, mainly because they violate the local authorities’ vehicular noise and emission laws. These laws are intended for the welfare of the people and the environment. You cannot just run anywhere and disturb others with the thick smog your vehicle blows up in the air and the ear-shattering noise your car produces. 

Can You Conceal Your Open Headers?

There’s absolutely no way to conceal an open header – except if you switch off your car. Traffic officers are equipped with the skills to spot you. Your car would stand out even surrounded by other obnoxious cars with decent exhaust systems, and I guarantee you’ll get caught and handed a fine once you hit the road.

Can Motorcycles Get Open Header Mods?

Of course! Motorcycle engines are similar to cars; the exhaust system where the headers belong is pretty similar too. However, there are still rules and procedures to mind before doing so.

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