Do I Bother? Is A Jeep 4.0 Header Worth It?

The benefits of a header are pretty clear-cut; higher horsepower and torque output on top of better fuel efficiency due to improved airflow through your engine bay with less restriction from OEM parts like exhaust manifolds or catalytic converters (if you still have them).

There’s also a weight-saving because these headers don’t require any gaskets or O-rings which means lighter weight versus stock cast iron manifolds. And lastly, you’ll often see a power increase in the 5-8% range which is pretty substantial given that it’s one of the few bolt-on modifications for your classic ride.

There are some negative aspects to consider as well and we’ll start with these; first off, these headers don’t make much sense on a lot of 4.0 applications. If you don’t have an aftermarket intake manifold and throttle body, then there’s not much point in upgrading your headers (which is why we’re focusing on this topic today).

, Do I Bother? Is A Jeep 4.0 Header Worth It?, Mad Digi

Secondly, it’s important to note that sometimes you’ll need to upgrade some other parts as well such as adding new high-flow catalytic converters to meet emissions standards where applicable. And lastly, there can be potential clearance issues depending on your specific truck and the application in question.

If you’re dead set on upgrading your 4.0L headers, we’ve broken down some popular options for you below. These are based on feedback from our customers and experts within the industry, but be sure to read online reviews as well because some people have had issues with certain brands. It pays to do your research before you buy!

Headers for your Jeep Wrangler or Cherokee are typically used to direct airflow to a different area of the motor, where it can be considered more efficient. This is especially helpful in cars or trucks which intake air from directly above the motor (and consequently, exhaust out of the center of the vehicle).

Here a header can direct airflow away from the center of the car and towards a more efficient side. They also serve to replace factory manifolds, which are typically designed to be cheaper rather than better.

Do Headers Make A Big Difference?

Cars with a V6 or V8 typically have both intake and exhaust manifolds, which can be replaced by headers. In this case, it is possible to measure the increase in power as a direct result of replacing the OEM manifolds with attractive aftermarket headers.

This includes some late-model Mazda Miatas, where significant gains can be found. However, even in this high-performance case, the increase will only amount to about 15-20 HP on average. This is because, while aftermarket headers can make great gains in horsepower (and torque).

There are many other factors that limit the overall power of an engine. Also, note that these types of changes should never be attempted without consulting a professional.

What About Jeep 4.0 Headers?

The 4.0 liter used in Jeeps such as the Wrangler TJ and Cherokee XJ models is notably different than most other engines. Many people upgrade to aftermarket headers for their jeep because the stock headers are prone to rusting out and if a leak is present, they will most likely need to be replaced.

In some cases, it can make sense to upgrade your Jeep 4.0 headers because the OEM manifolds are inefficient and cause hot spots in the engine bay which may lead to overheating. In addition, many people who spend a lot of time off-road with their Jeep are looking to upgrade the 4.0 for performance purposes anyway, so upgrading your exhaust manifolds can make sense in this case as well.

However, you should not simply go out and replace your Jeep 4.0 headers because you have heard that they will increase power because this is simply not true.

Do Headers Make The Car Louder?

The car sound can generally be reduced by reducing the backpressure in the exhaust and muffler. A header will generally have less of an effect on this aspect than a similar exhaust would because a header is (by its nature) not as restrictive. An aftermarket exhaust will help in this area more than an equivalent header will.

Headers will change the sound by changing the way in which sound travels through the exhaust, but will not cause an increase or decrease in decibels.

, Do I Bother? Is A Jeep 4.0 Header Worth It?, Mad Digi

How Much Do Jeep 4.0 Headers Cost?

The cost of headers depends on many factors, including how custom they are, what material they are made out of, and where you purchase them. The least expensive headers typically cost $1000 and the most expensive, well over $4,000.

What Is The Difference Between Headers and Manifolds?

The main difference between a header and a manifold is one of practicality. A manifold takes the output and distributes it in an even, smooth manner to each cylinder. You can think of manifolds as “plumbing,” whereas headers are more like “piping.”

A header has tubing which connects to each of the cylinders of the engine, where a manifold will have an even distribution of tubes.

Header exhaust manifolds are more efficient than aftermarket headers by nature, but they also tend to be more expensive. However, depending on your specific application you may find that this is still more effective than an installed aftermarket header.

While the average car will not see much of a difference between an aftermarket header and stock manifolds if you are looking for something more specific (like improved gas mileage) there are many factors to consider before choosing one.

Are Headers Bad For Your Engine?

Headers will not hurt your engine. If anything, they actually improve its longevity because you removed the restrictions! It’s like running with 5 lb ankle weights as OEM exhaust manifold.

But infinitely more satisfying to watch that baby go downrange burnin’ rubber at over 500hp/ liter
2 wheels on an aluminum English roadster 3 days ago in Leicestershire when I found out how much easier it is without those pesky factory resonators so we made a video about our findings.

The sound can generally be reduced by reducing the backpressure in the exhaust. A header will generally have less of an effect on this aspect than a similar exhaust system would, because a header is (by its nature) not as restrictive. An aftermarket exhaust will help in this area more than an equivalent header will.

How Good Is The Jeep 4.0?

The Jeep 4.0L is a solid, reliable, and efficient design that has been used in many Jeeps for over 20 years. We all love our first Jeep Wrangler for many reasons. It has a good balance of power and economy and is not known to cause major issues (unlike certain other engines which wear out quickly or require expensive repairs).

It has kept production costs low and it also happens to be one of the best choices for upgrades, as many aftermarket companies make parts specifically for this model.

Is It Worth Upgrading My Jeep Headers?

Not unless you’re planning on improving other parts of your jeep as well. Unlike many Jeeps, the 4.0L is designed to be reliable and efficient enough to run without an upgrade for a long time. This means that there will not be any immediate performance gains from upgrading it and it will likely be cost-ineffective as well.

Instead, upgrading other parts of your Jeep will give you a better overall improvement. An enhanced suspension will help with handling and braking performance while a new exhaust system can improve your engine’s sound and power output at the same time.

A high-quality upgrade done to these systems can produce similar or greater effects than a header would but at a much lower price. At this time, it is not recommended to upgrade the Jeep 4.0 headers for reasons already mentioned above.

Is A Jeep 4.0 Header Worth It?

No, I wouldn’t recommend you do it because it’s not going to have much of an effect on your jeep, you should upgrade other parts of your jeep before it. A Jeep 4.0 header can improve the power and torque of your truck’s motor. The header is attached to the engine by welding, and it will replace the original manifold as well as the catalytic converter.

, Do I Bother? Is A Jeep 4.0 Header Worth It?, Mad Digi

Replace Your Jeep 4.0 Headers


  • New Jeep 4.0 headers (2)
  • New exhaust gasket (2)
  • New header bolts (4)
  • New catalytic converter hangers (2)
  • Loctite

Optional Parts

  • New exhaust manifold studs (8 lug nut size, typically 5/8″)

Tools Needed

  • Socket set w/ ratchet and extensions up to 18″
  • Pipe wrenches sized to your exhaust pipe
  • Soldering Iron
  • Silver solder (get from welding supply store)
  • Torch fitted with a MAPP gas tank or “torch kit” from home depot or lowes

How To Do It

  1. Open the hood and disconnect the negative terminal on your Jeep 4.0 battery with a socket wrench.
  2. Remove the heat shielding from around the exhaust manifold and catalytic converter (it’s held in place by metal springs, typically 10 or 12)
  3. Disconnect the tubing from the rubber hangers at either end of the catalytic converter and the exhaust manifold.
  4. Remove the Jeep 4.0 header bolts and set them aside, along with the heat shields and catalytic converter hangers.
  5. If you haven’t done so already, install new studs (if applicable) into your old exhaust manifold and tighten down until they won’t turn anymore. remove the manifold and set it aside.
  6. Remove your old exhaust manifold gasket (if applicable) by prising into one of the manifold’s studs with a flat head screwdriver, and getting under the lip of the manifold itself – work it back and forth until it pops off.
  7. Be sure to clean up all surfaces using brake cleaner or mineral spirits when you’re done with this step.
  8. Install your new exhaust manifold gasket, if applicable, then lay your new header into place on the block and install the bolts loosely. Reference your owner’s manual for any torque specs – most expect 20 ft-lbs of torque to be delivered.
  9. Use your MAPP or propane torch to solder the exhaust manifold studs into place – do not use a propane/butane mix, or acetylene – it must be a full propane tank! Keep the heat moving around the entire stud so that you don’t burn the stud or the manifold – solder will flow when it reaches 500 degrees Fahrenheit, so check your temp with a regular propane torch. When you start seeing bubbles in the solder when you heat up the stud, stop heating and pull off your MAPP/propane torch immediately. Solder will solidify when it cools so don’t move on to the next stud until it’s solidified.
  10. If you don’t have a MAPP/propane torch, use a soldering iron and silver solder to attach your new Jeep 4.0 header bolts to the exhaust manifold – be sure to coat the bolts with a little oil before applying heat to them! This method is slightly harder to accomplish, but it is possible.
  11.  If you bought new header bolts for this step, apply some thread locker (called “Loctite”) now – if not, skip ahead to step 9.
  12. Slide your new catalytic converter hangers into the slots on the Jeep 4.0’s frame rails.
  13. Apply some thread locker to the Jeep 4.0 header bolts and insert them into their respective holes on the block, then tighten until they are snug – don’t over-tighten!
  14. Re-connect your tubing to the rubber hangers on either end of the new catalytic converter and re-install the heat shielding.
  15. If applicable, re-attach the heat shields to their proper location on top of the header with the nuts that held them in place originally.
  16. Re-attach your negative terminal to your Jeep 4.0 battery, then start your engine to ensure there are no leaks. (Wiki)

Main Takeaways – Is A Jeep 4.0 Header Worth It?

A Jeep 4.0 header may be a good choice for your vehicle, especially if you want to improve the motor’s efficiency or replace the existing manifold. Even though it may not require upgrades as frequently as some other engines, there are many aftermarket parts available and it can be a good choice for those who are reliable but inexpensive.

Many Jeep mods are designed to work with them, so they’re worth considering. . Note that this article is written with the express intent of giving you information so that you can make an informed decision about your Jeep 4.0 header – it is not designed to be copied verbatim, either in whole or in part.


Four Wheeler
Redline 360
Wiki Answers