Jeep Wrangler JK: Axle-Back Exhaust Systems and Uses

An exhaust system is almost never made of any truly continuous parts. In fact, they break up into pieces. Not only does this make it easy to install the system, it also makes it easy to swap out components when needed.

A cat-back exhaust is the most traditional type of aftermarket exhaust system. It replaces everything behind the catalytic converters. The idea is to prevent one from tampering with the factory catalytic converter and aggravating Johnny Law. It also saves a ton of money for the end user as catalytic converters are not cheap. The axle-back design follows the same principles, but in an even more affordable package.

It’s a bit of a bummer this setup is something one can only find on a JK Wrangler, but there is a good reason. If you were to flip a Wrangler over and look at its belly, you can spot the exhaust system easily. Just like any other Wrangler the factory pipe follows the undercarriage and exits below the rear bumper.

The difference is where the muffler is located. On TJs and YJs the muffler is located before the rear axle and the tailpipe simply runs over the axle and out the rear. On a JK Wrangler the muffler is located behind the rear axle. This design is what gave designers the advantage to replace the segment behind the axle only.

The biggest benefit to using an axle-back exhaust as opposed to swapping in a cat-back system is cost. We all know parts cost some serious money, and there are a lot of parts for JKs. Let’s face it. Lift kits and other JK enhancements aren’t cheap, so if you could save a few dollars on the exhaust you’re going to be in better shape down the road.

Now, you might be saying to yourself it might be sacrilegious to replace only part of the exhaust with brand new pieces when the rest of the exhaust would remain the same. Though that may be true for older vehicles, JK Wranglers are still fairly young so it really won’t hurt much to do so.

These kits may be much shorter than the cat-back exhaust system, but this doesn’t take the bite out of the bark. The sound and flow really come from the muffler. The factory muffler can be rather restrictive, slowing air down and holding back performance.

The rumble you’re after also comes from the muffler, so saving a few dollars and grabbing the axle-back exhaust over the cat-back is kind of a no brainer.
In summary, the benefits of the axle-back setup are as follows:

• Affordability over other exhaust systems
• Improved performance
• Better sound
• Quicker installation

When replacing such a small portion of the exhaust system it’s hard to imagine there could be different types. There are some key variances to take note of though. First and foremost is material.

As with most exhaust systems, you can find stainless steel and aluminized steel. Stainless is perfect for the Jeep way up north in the rust belt. Aluminized is great for guys outside the region, but not always. Let’s say you decided to pick up this system and you don’t expect the rest of the exhaust to live much longer. Aluminum is a good way to save yourself the money. 

The exhaust can also split here. With cat-back exhausts, one can pick up a type that would convert the set up from a single-pipe exhaust to a dual. Usually, this happens at the muffler where a single inlet dual outlet muffler is used to split the exhaust.

It’s because of this that a dual rear exit and still be used with this type of exhaust.
Colors also vary here. Black exhaust tips are all the rage in today’s day and age. It’s only natural manufacturers would offer these kits with variant colors in exhaust tips. It is also worth noting that the whole kits can come in different finishes as well. 

When comparing kits side by side you may notice that the mufflers all look relatively similar yet produce much different sounds. This is because the magic happens within the casing itself. The idea behind all mufflers is to manipulate the exhaust note. The way this is done can vary.

Chamber type mufflers contain a series of chambers that give the car a deep note without blowing your eardrums out. Absorptive mufflers may appear a little different than chamber type mufflers on the outside, but on the inside they are worlds apart. The exhaust can pass freely through the muffler.

On the walls of the muffler you would find packing materials that really dial in the note. These types are more free flowing, but are much louder. There are combination mufflers which land right in the middle of the road. It’s important to keep in mind each manufacturer has their own formulas for each type.

This means they will all have signature notes, meaning you will have to do your homework to ensure you get the sound you find best.

One of biggest reasons to choose one of these axle-back kits is affordability over other exhaust systems. It’s likely you came into this expecting to spend a set dollar amount, and you’re now sitting with a few extra bucks wondering what you could invest it in.

Well, you’re Jeeper so putting some of that leftover cash toward another part in the plethora of options available is always a good choice. If you’re wondering what other product you could purchase to take advantage of the gained performance potential there are a few things you could do.

You can upgrade to a cold air intake; getting air in is just as important to the engine’s performance as getting air out. A computer programmer is also an excellent choice, and will help you dial in your engine’s programming for even more horsepower.