Best 6.7 Cummins Exhaust Manifolds – 2021 Ultimate Review

| Last Updated: December 25, 2021

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An exhaust serves a car in multiple ways. 

It is necessary to remove the hot gases from the engine to prevent overheating, and it removes pollutants and subdues the noise of the engine. Without it, the car would not function at its best. 

Exhaust manifolds utilize an efficient design to fulfill the purpose. This article will talk about exhaust manifolds manufactured by the renowned car appliances brand: Cummins.

Comparison of the Best 6.7 Cummins Exhaust Manifolds

  • It is engineered for high performance
  • This product is quite easy to install
  • It is made from high-quality materials
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  • Can be fitted on a variety of models
  • Made with a durable construction
  • Quite easy to install
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  • Best for the Money
  • The product will drastically improve performance
  • Highly precision engineering and manufacturing design
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  • Made strong and durable to last longer
  • Comes with high-quality engineering design
  • Easy to install on vehicle
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  • Can be used on different models
  • Will help to improve overall performance
  • Made strong and durable
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What is an Exhaust Manifold?

As we know, the main function of an exhaust is to direct the hot gases released as a result of combustion from the engine compartment out of the car, and to do so; it requires a layout of pipes. An exhaust manifold is present in all internal combustion engines and has multiple pipes for collecting gases from each chamber of the engine, hence, the name exhaust manifolds. 

In these exhausts, gases from multiple cylinders are delivered into one exhaust pipe. Burnt gases from all the chambers, either four or six, are sent to the exhaust pipe where any unused gas is burned, utilizing the pipe's very high temperature. This increases the efficiency of the engine. The system also houses an oxygen sensor to monitor the amount of oxygen required for the combustion.

What Are The Symptoms of a Bad Exhaust Manifold? 

A failing or bad exhaust manifold portrays a few symptoms that are enough to alert the driver of prevailing problems. In case any of these signs are observed, the car engine should be immediately checked for the cause of symptoms. Let’s see how these signs and symptoms manifest themselves.

Reduced Engine Efficiency

Since an exhaust manifold houses and makes sure that all gases are burnt, damage to it or a leak will result in the escape of these gases before they are fully utilized. Hence, this would not only lead to the problem of keeping a steady combustion temperature but would also result in the loss of unused gases. Overall, this would negatively affect your engine’s performance and would be portrayed as such. 

Signs might appear in the form of a reduction in power, reduction in acceleration, and inefficient fuel utilization, leading to the more frequent need for a fuel refill.

Noisy Engine

Another major sign of a failing exhaust manifold is a noisy car. The noise is usually produced by leakage or crack in the exhaust and appears as a very loud hissing or tapping noise coming from the engine bay. The noise is easily distinguishable as something out of the ordinary. Also, it will increase with an increase in acceleration.

Smoke or Burning Smell Coming From the Engine

If an exhaust breaks or cracks, it results in the release of very hot gases to the surrounding components. These gases are hot enough to cause burning damage to the nearby plastic and electrical components. Burning of these parts produces the smell and might also produce some smoke emerging from the engine bay. This serves as a clear indication that your exhaust might be damaged.

What Should I Look For When Buying a 6.7 Cummins Exhaust Manifold? 

To make sure you end up with the most suitable exhaust manifold by Cummins for your vehicle, consider a few things. These are described below.

Pipe Size

Before settling on an exhaust system, make sure that the exhaust pipe diameter is suitable for your vehicle’s engine. A large pipe is not always the best option, and it does not lead to better power and performance for all vehicles. 

To obtain the perfect balance between gas flow velocity and back pressure, it is crucial to get the right-sized pipe for your engine. This way, the burnt gases would efficiently leave the system at the right time. 

Luckily, the industry usually utilizes a chart that tells you the correct diameter needed for your engine, based on the engine’s horsepower and the vehicle’s size. Utilizing the chart and consulting a good mechanic would be enough to lead you to the right track.

Construction Material

What your exhaust manifold is made of greatly affects its efficiency. Since it harbors very hot gases, the material used for construction must be able to withstand the high pressure. 

Usually, cast iron and stainless steel serve as good examples of material used for exhaust manifolds. They can bear the high temperature constantly without melting or changing form under high temperatures. They are also good conductors of heat and provide enough insulation to keep the exhaust at the required temperature for the combustion of unused gases.

Abide CARB Law

In the United States, and especially in the California region, another very important consideration is the CARB Law. The CARB law was formulated to protect the environment and, more specifically, the air to ensure a healthy environment.

Any car that is utilizing an engine not deemed safe by the California Air Resources Board (CARB) is considered illegal. Hence, before buying the Cummins exhaust manifolds, make sure they comply with the law.

BD Diesel 1045965

Review of the Best 6.7 Cummins Exhaust Manifolds

Cummins is a well-known and leading name in manufacturing car engines and accessories. They are known to produce very competent and efficient engine systems. To pair a high-performance engine with a good exhaust is only reasonable. In this section, we will look at some of the best exhaust manifolds for Cummins.

Best Overall:
BD Diesel 1045965


  • Offers reduced backpressure for efficient airflow
  • Features expansion joints to prevent cracking of pipes
  • Capable of withstanding extreme temperature and vibrations
  • Quicker spool to lessen the time required to reach full turbo pressure
  • Attaches to the OE turbochargers to ensure combustion of unused gas


  • Only for pickups, not suitable for smaller vehicles like cabs and chassis

What Recent Buyers Report

Recent buyers had good thoughts regarding this exhaust. It appeared to them as a piece of good-quality construction that can withstand the constant expansion and contraction that comes with excessive use of the car. When they used it, they were able to feel a big improvement in the engine’s performance right away. The system lines up the bolts easily and holds it in position. 

Why it Stands Out to Us

Quite a few features make this exhaust manifold stand out. The expansion joints are a very useful addition that prevents the system from cracking under higher temperatures. The joints' ability to expand allows them to withstand the pressure and offer optimal performance at high temperatures that arise due to long drives. 

In addition, the positioning with the turbocharger and the quick spool greatly enhance the efficiency of the engine. The unburnt gases are caught and kept in the exhaust while the quick spool charges the turbo quickly. The unused gases are then burnt after the turbocharger is spooled up, without much delay or before they can escape. 

Bottom Line

The BD Diesel 1045965 is a great option for an exhaust manifold. It has features that will work well with the high-performance engine of big vehicles. Its high tolerance for temperature and vibration and the joint expansion make it ideal for heavy-duty vehicles.

BD Power 1045995-T4


  • Tapped and Pre-drilled NPT ports give better flow
  • Features a T4 flange to accommodate aftermarket turbochargers
  • Turbo flange is mounted at a 20ͦ angle to facilitate mounting larger turbochargers
  • Heavy cast HiSi Ductile iron construction and heat expansion bolts for withstanding high temperatures


  • Not compliant with the CARB law and not for use on a stock turbo application

What Recent Buyers Report

For most of the buyers, this unit served well. To begin with, the installation was simple and hassle-free, and the machinery was a perfect fit. Some reported that the 20ͦ angle positioned the exhaust too close to the A/C pipe, so wrapping the A/C pipes in heat protectant sheet or moving them a bit far did the trick for them. Other than that, the construction was solid and performance optimal.

Why it Stands Out to Us

This exhaust features a very intelligent layout. It is built to cater to large Turbochargers like S400 or S500. The high-quality cast iron conducts heat well, maintaining the temperature required for burning unused gases while the expansion joints make sure that the metal does not break due to the rise in temperature.

Another great feature is the efficient gas flow that comes with a ported design. There are ports and runners on this exhaust that match the inlet gasket within 0.03,” allowing for very good airflow and reduced backpressure. As a result, hot gases are efficiently removed from the system when not needed anymore. 

Bottom Line

Overall, this exhaust manifold also serves as a good option for a Cummins because of its ability to withstand high temperature and facilitate airflow with its ported design. It would be great for those who use aftermarket turbochargers or large turbochargers. 

Best for the Money:
AFE 46-40054 BladeRunner


  • Flange walls are thick, reducing the risk of cracking
  • Outflows factory exhausts by 49%, giving better performance
  • Composed of ductile iron to impart strength and temperature tolerance
  • Ports and a merged runner design reduce backpressure and enhance airflow
  • Package includes six-port gaskets to make for a complete kit and hassle-free installation


  • Not compliant with the CARB law 

What Recent Buyers Report

This exhaust manifold gave recent buyers easy installation and smooth working. It bolted up nicely, and the dual axillary EGT Probe ports facilitated in a problem-free installation. The engine performance was observed to get significantly better with the upgrade to this exhaust, and the fuel efficiency was seen to improve as well.

Why it Stands Out to Us

The pipes' walls and other parts of this exhaust are thick and composed of cast ductile iron. This renders the exhaust a very strong and dependable piece of machinery. The design has a ported and merged runner layout, which reduces the back pressure on the exhaust gas, preventing them from leaving the system. The reduced pressure due to the merged runner design improves the exhaust flow so that the burnt gases are released out. 

In addition, this exhaust comes with six-port gaskets that you don’t have to buy separately. Everything you need to install it is included in the kit. The dual auxiliary ports also facilitate the installation and testing of equipment.

Bottom Line

With this exhaust, you get some of the best features at a very reasonable price. The 49% enhancement over the factory exhaust manifold greatly affects the engine efficiency and throttle response. Combine these features with a solid body, and you get the best bang for the buck.

4. BD Power 1045996-T4 Wastegated


  • Kit includes Wastegate Block-Off plate and clamp
  • T4 flange for installation to aftermarket turbochargers
  • Features 2 NPT tapped, and pre-drilled ports sized 1/8”
  • Cast iron construction retains heat, and the expansion joints prevent cracking
  • Turbo flange is positioned at an angle of 20ͦ to accommodate large turbochargers


  • Kit does not include a replacement gasket or manifold bolts

What Recent Buyers Report

Most recent buyers were happy and satisfied with their purchase. They found the exhaust to be a nice adjustment for their aftermarket turbochargers or S400 or S500 size turbochargers. None of these buyers were from California however, because this exhaust cannot be used in that region.

Why it Stands Out to Us

This exhaust, too, has features that make for a good car part like the ones discussed above. A solid cast iron construction with expansion joints keeps the heat retained but also prevents the system from cracking. Large-sized turbochargers or aftermarket turbochargers require specially fashioned exhausts to fit them, and this exhaust acts as a perfect fit. 

The ported design gives a good airflow and keeps the expulsion of burnt gases in check. The BD Power 1045996 needs to be used with a TurboSmart 45mm HyperGate. The gate needs to be procured separately; however, the kit does come with a Wastegate Block-Off plate and clamp that are required to complete the installation.

Bottom Line

For anyone living outside California, this exhaust is also an option to be seriously considered. It can fit large turbochargers, deeming it suitable for large vehicles. The high-temperature tolerance makes it suitable for heavy-duty engines taken for long drives. Over long distances, the exhaust maintains the airflow and efficiently burns the unused gas, hence adding fuel efficiency.

5. ATS 2049202326 Pulse Flow


  • Kit includes an engine-to-manifold gasket for installation
  • T3 flange configuration to suit aftermarket turbochargers
  • Features an exhaust backpressure port to facilitate airflow
  • Front and Rear EGR ports to retain the factory system as required
  • Ball flange design to prevent breaking and cracking during contraction and expansion of parts


  • Kit does not include exhaust manifold gasket, and the exhaust cannot be used for stick application

What Recent Buyers Report

ATS 2049202326 Pulse Flow exhaust flow designed for the T3 application was quite popular amongst its users. It features a design that facilitates airflow, helping not only in the removal of burnt gases but also in the combustion of unburnt gases. Moreover, the EGR ports retained the factory system, which was a huge advantage.

Why it Stands Out to Us

This exhaust by ATS was designed as a bolt-on upgrade. It features an EGR port that closely monitors the recirculation of gases as required by the exhaust system. The design features a T3 flange that can fit aftermarket turbochargers. Since it is not for use for stock application, the exhaust has front and back EGR ports that retain EGR factory systems.

The exhaust utilizes an exhaust backpressure port for optimal airflow, lowering the backpressure that forces the combustion gases to stay in the system. As a result, the airflow is smooth and unhindered. A ball flange also helps prevent the cast iron from breaking or cracking due to constant expansion and contraction of the system.

Bottom Line

The exhaust by ATS comes with manifold gaskets included in the kit to aid installation. Other than that, the T3 flange can attach to aftermarket turbochargers while the EGR ports regulate airflow and retain factor systems. Lastly, a ball flange ensures that the walls of the system don’t break from expansion. All in all, this exhaust is a pretty decent deal.

How Long Does it Take to Replace an Exhaust Manifold? 

In case you have a broken or damaged exhaust manifold, you will have to visit your car mechanic. Depending upon the intensity of the damage, the exhaust would either be fixed or replaced. 

If your mechanic recommends a replacement, then this might take some time. For proper installation, it might take the shop anywhere between two and three hours. This time includes removing the damaged exhaust, then positioning the new one followed by bolting it in. After the exhaust has been securely bolted in its place next to the turbocharger, it would be time for you to take the car out for a test run.

Make sure that after the replacement, the car does not show any symptoms that lead to the diagnosis of the damaged exhaust manifold, nor does it show any new problems. All this will take around three hours with more time required to make any adjustments the need of which might have arrived during the test run.

How to Install a 6.7 Cummins Exhaust Manifold

Follow the steps mentioned below to install your 6.7 Cummins Exhaust Manifold. These are simple and easy to follow for anyone with some knowledge of the vehicle’s systems.

  1. Unpack your package with the exhaust manifold and lay out the contents near the vehicle.

  2. Raise your vehicle using a car jack enough so that you can bring the exhaust under it easily.

  3. Begin at the rear end of the vehicle by removing the muffler first. If the vehicle has two mufflers, then remove both.

  4. Then remove the middle bolted part of the exhaust from the catalytic convertor.

  5. The flange connected to the catalytic converter may be connected by two to three bolts that will need to be removed.

  6. After the hardware is removed, take the piping off the rubber hangers. Next, remove the rubber hangers and place the new ones.

  7. Slip the new piping on the new rubber hangers as well.

  8. Now slide the new muffler onto these rubber hangers.

  9. Between the catalytic convertor and the new exhaust, install the new gasket.

  10. With the help of new hardware, fasten the flange together.

  11. Tighten using the hand.

  12. There is a flange that joins the middle piping to the muffler. Locate this flange, install a new gasket, and fasten it together.

  13. Finally, tighten the bolts well so that all parts are securely in position. 

  14. While the vehicle is raised, start the engine. Check for unusual noose, smoke, or smell. If there isn’t any, then you have correctly installed the exhaust. If you feel something unusual, check the connections again and make sure no part of the engine burns by coming in contact with the exhaust.

  15. Lower the car to the ground.

All of these steps might seem confusing. Hence, we’ve added a video that demonstrates the entire process. Have a look:


Cummins manufactures heavy-duty and robust engines that require an equally well-performing exhaust manifold. The exhaust manifold, coupled with a Cummins, should be able to withstand high temperatures and have a solid construction and a good airflow. The options discussed above satisfy all three requirements. All you have to do is see which one suits you the best.

People Also Ask

Investing in car parts is a serious deal. It affects the working and health of the car as well as the safety of the riders. Every part must be procured with diligence and after proper research. In the article above, some areas of discussion regarding exhaust manifolds might have been left unanswered. In this section, we will address some of those questions.

How Hot Does an Exhaust Manifold Get?

The exhaust manifold can get very hot as gases concentrate here right after combustion. For this reason, the temperature of an exhaust manifold may go up to 1200F. Other than this part, it is rare to find such high temperatures along with the engine. Hence, care must be taken while dealing with exhausts, especially right after you have been on a drive. It is best to let the exhaust cool before you inspect it.

When Do You Need a New Exhaust Manifold on a Cummins?

In case you experience noise, smell, or burn coming from the engine, you might need a new exhaust manifold. The noise may be due to cracked parts and exhaust gas release, causing a hissing sound. The smell might be due to the adjacent plastic parts burning because of the leaking hot gases. And the smoke might also be the result of this burning. 

Why is My Exhaust Manifold Glowing Red?

Even though exhaust manifolds get very hot, a glowing red color might be alarming. This might be because the hot gases are not being released at the optimal rate due to some constriction in the pathway. It could also result from a lean air-fuel mixture or slow ignition timings. In either case, visit the mechanic at your earliest to solve the problem.

Sean comes from the forums actually and drives an OBS Ford. He writes fantastic DIYs and knows his way around a camera, too. We keep him caffeinated and away from DPF filters to avoid another rant about recent emissions restrictions.