CAT-BACK VS. AXLE-BACK EXHAUST: WHAT'S THE DIFFERENCE?

WHAT IS A CAT-BACK EXHAUST SYSTEM?

Cat-Back exhaust systems replace everything from the catalytic converter back. That includes the mid-pipes, mufflers, and exhaust tips. Cat-back systems have an impact on sound, performance, and appearance. This trio of benefits makes it one of the most popular exhaust modifications.

Cat-Back Systems:

• Deep Throaty Sound
• Horsepower Gains
• Easy Installation
• Most Popular Exhaust Mod

How Do Cat-Back Systems Work?

Cat-back systems typically use pipes with a larger diameter than stock exhaust pipes. This helps reduce backpressure, which can improve horsepower. The horsepower increase varies, depending on how restrictive the stock pipes were.

One feature you’ll notice on a lot of cat-back systems from high-end manufacturers like Roush, MBRP, and Ford Performance is “mandrel-bent” piping. Mandrel bending keeps the bends in a pipe from creating a pinch. This keeps the pipe’s diameter consistent and creates a deeper, throatier sound.

Are Cat-Back Exhausts Legal?

Because the catalytic converter is left intact, most cat-back systems are legal and emissions-compliant. Where some installers run into issues is with the decibel rating of their exhaust. Depending on local laws and statutes, there may be restrictions on how loud your exhaust can be. California is a famous example of this.

Cat-back systems are available with a wide variety of exhaust volumes and notes. That means many cat-back systems are 50-state legal.

Cat-Back Exhaust Sound

One part that most cat-back systems don’t come with is a resonator. Resonator deletes are a popular exhaust modification on their own. Though removing the resonator doesn’t make the exhaust louder, it does allow for further customization of the exhaust note. Removing the resonator also removes a lot of weight. The result is a lighter overall exhaust with a totally different sound. Many people describe the cat-back sound as deep and throaty.

WHAT IS AN AXLE-BACK EXHAUST SYSTEM?

Axle-back systems replace everything from the rear axle back. Axle-back systems typically include the muffler, exhaust tips, and sometimes a small section of piping. For vehicles that already have good intermediate and mid-pipes, axle-back kits provide improved sound at a much lower price than cat-backs.

Axle-Back Systems:

• Rich, Deep Sound
• Wide Range of Looks
• Lower Cost
• Easier Install

How Do Axle-Back Systems Work?

Typically, axle-back systems don’t improve performance much, if at all. They do replace the muffler, which can free up airflow, but the gains are minor. Since they replace such a small section of your exhaust system, installation of an axle-back kit is usually very straightforward.

Flexibility for More Exhaust Mods

Another reason to get an axle-back over a cat-back is that it gives you the freedom to mix and match your exhaust system pieces. Cat-back systems come with a mid-pipe, but you might prefer to select your own. Considering the differences between X-, Y-, and H- pipes, this makes sense. Installing an axle-back and a mid-pipe is essentially building your own cat-back system. You just have more flexibility in what parts it’s made up of.

Axle-Back Exhaust Sound

High-quality axle-back exhaust systems also use mandrel-bent pipes. These pipes eliminate tinny notes and create a deep rumbling effect. Axle-backs usually sound richer and deeper than stock exhausts but don’t quite have the rumble of a cat-back.

 

IS A CAT-BACK OR AXLE-BACK SYSTEM BETTER?

It seems straightforward. While axle-back systems improve sound and looks, cat-backs do all that and improve performance. But that performance boost comes at a higher upfront cost. You can also pair mid-pipes with an axle-back later for the same performance boost and have more flexibility in what you choose.

The answer is that either exhaust system can be the best fit, depending on your build.

Get an Axle-Back If…

If your primary concern is how your exhaust sounds, then an axle-back is a great choice. Axle-back installations are quick and easy, and they give you flexibility for future exhaust mods. This makes them a great choice if you’ve just started wrenching on your own.

Axle-back exhausts are also cheaper than cat-backs. Many of the same brands that make great cat-backs make equally great axle-backs.

If you want an inexpensive system that sounds and looks great, axle-backs are the way to go.

 

Get a Cat-Back If…

If you’re focused on finding a “one-and-done” exhaust system upgrade that improves sound, performance, and appearance, then a cat-back kit is your smartest choice. While you might save some money now with an axle-back, if you’re already planning more exhaust mods, doing them together will save you money and time. You’ll also know that the parts are compatible with each other.

 

WHAT IF YOU CAN’T DECIDE WHICH SYSTEM TO GET?

If you’re still unsure which exhaust system is right for you, it never hurts to ask the audience. We surveyed our customers to find out which exhaust upgrade they’d go with, and a cat-back exhaust was the clear winner.

Cat-backs are the most popular exhaust mod for a reason. They offer a great trio of benefits and have a relatively easy installation and affordable price. The only challenging part will be choosing just the right system for your ride.

 

An effective vehicle modification that can provide both aesthetic and performance improvements is an aftermarket exhaust system. Generally, bolt-on kits can be installed by the novice to skilled DIYer and come in two popular configurations: axle-back and cat-back. But how do you know which one is right for you? Traditionally, people that are looking for more sound than their stock parts produce turn to the axle-back option, which will increase overall volume and produce a more aggressive sound. For those looking to not only increase sound and volume but performance as well, the cat-back is the best option. Read along below as we breakdown the features and benefits of both options and discover which one is right for you.

WHAT ARE AXLE-BACK EXHAUST SYSTEMS?

An axle-back exhaust system includes the parts after the rear axle of a vehicle, which usually consists of the muffler, tailpipe and tips. (Axle-back and cat-back configurations are vehicle dependent, and sometimes only one is available for a particular make/model.) Axle-backs are a great choice for a number of reasons

BENEFITS:

• Focuses on modifying sound quality

• Provides aggressive tone compared to stock system

• Easy bolt-on installation

• Less impact on your wallet due to lower cost

 

WHAT ARE CAT-BACK EXHAUST SYSTEMS?

Cat-back exhaust systems refer to all of the components that exhaust gasses flow through after exiting the vehicle’s catalytic converter. Typically, that includes a mid-pipe, muffler, tailpipe and tips. Cat-backs generally yield increases in performance, due to the more efficient flow of exhaust through upgraded parts like larger diameter tubing and better flowing mufflers, as well as improved sound and reduced weight.

 

BENEFITS:

• Focuses on modifying sound quality and increasing exhaust system performance
• Creates a more aggressive exterior tone
• Easy bolt-on installation
• Improves exhaust flows
• Replaces exhaust system from the catalytic converters back to the mufflers
• Reduces the overall weight of the vehicle

 

 

Because these types of exhaust systems are installed after the emissions monitoring systems of a vehicle, they won’t impede its ability to measure emissions. However, you must be aware of your local noise regulations and adhere to them. With relatively short install times when using a high-quality system from MagnaFlow, exhaust modifications can yield the instant gratification of your ride sounding as fast as it looks.

Axle-back Vs. Cat-back

The easiest way to understand the difference between axle-back and cat-back systems is to think about where each part of the exhaust system starts.

The “axle” refers to the back, or rear, of the car (where you’ll find the wheels), and where it connects with the rest of your car; this connection point is called an “axle”. For example, on a 4-cylinder vehicle, there are four separate axes: one for each wheel.

On a V6 or V8 vehicle, there are two axles: one for even-numbered cylinders and one for odd-numbered cylinders. Finally, on a flat engine or motor that contains no distinct parts, such as a rotary engine or motorcycle engine, there is only one axle.

The “cat” refers to the catalytic converter, a device that uses catalysts and heat to break down harmful emissions before they can be released into the air as exhaust gases. In modern cars, this takes place not in the muffler but inside the exhaust itself.

Generally speaking, a cat-back system is simply an aftermarket exhaust with a visible component made from tubing connecting the axle to the muffler. As such, you’d use this term for any car that has a fully exposed section of tubing running from its rear end to where it connects with the actual muffler – anything apart from a true “axle-back”.

On an axle-back system, by contrast, the catalytic converter remains in place and there is no visible component extending from the axle to the muffler. These types of systems tend to be less expensive than cat-back systems and they produce a slightly louder sound than their counterparts.

It’s important to note that you can perform one modification without performing another: just because your car currently has an axle-back exhaust doesn’t mean you need to switch it out for a cat-back system; it simply means you’d enjoy some of the benefits of such a system (like improved fuel economy) by doing so.

Advantages and Disadvantages of the Axle-back Exhaust System

 

The major advantage of an axle-back system is its simplicity. Because it contains no components that extend from the axle to the muffler, it’s often less expensive and easier to install than a cat-back system. It also produces a louder exhaust note because you’re not replacing any pre-existing components that mute the sound.

However, this type of system does have a few disadvantages, particularly when it comes to performance. The primary drawback here is reduced fuel economy: while better than nothing, an axle-back system will cause your car to lose some of its peps compared to if you had kept things stock or added a cat-back system instead.

By installing only the very beginning portion of your aftermarket exhaust at first, you’ll be able to safely and effectively improve your vehicle’s overall performance while minimizing the impact on its fuel economy.

Advantages and Disadvantages of the Cat-back Exhaust System

 

The major advantage of a cat-back system is its improved fuel economy. Since it replaces the part of your exhaust system immediately behind the catalytic converter, you’ll be able to enjoy better power and better gas mileage than what you’d get with an axle-back system.

It’s also considerably more affordable than an axle-back system, particularly when compared with other aftermarket modifications such as cold air intakes and turbochargers.

However, because the catalytic converter remains in place and isn’t replaced, this type of exhaust doesn’t make nearly as much noise (or sound cool) as an axle-back system does; only by taking out the catalytic converter itself can you achieve a truly throaty tone.

This isn’t usually a concern with sedans or other types of cars, but if you drive a sport utility vehicle (SUV) or pick-up truck you might need to learn the specific procedures for removing your particular model’s catalytic converter.

Which Is Better? The Axle-back or the Cat-back?

When it comes down to choosing between an axle-back system and a cat-back system, there’s no right answer. Both types of systems offer their benefits and disadvantages; the choice is really up to you.

If your primary concern is performance, you’ll be better off with a cat-back system. If your primary concern is price, you’ll probably prefer an axle-back system (provided it doesn’t conflict with any noise ordinances in your area).

How To Choose Which Is Suited For You?

When deciding which type of exhaust system is right for you, it’s important to examine your priorities to decide which one will be more beneficial in the long run. Do you place a higher priority on performance or price? What about noise levels? These are just some of the questions that you’ll need to ask yourself when making this decision.

Performance vs. Price

If you’re looking for the absolute best performance possible, a cat-back system is your best option. If you’re on a tight budget, however, an axle-back exhaust might be more affordable in the short term but will ultimately cost you more money if it’s ever time to replace it with something better.

Noise Level

Similar to how performance is directly related to price when dealing with an axle-back system, the noise level is directly related to price when dealing with a cat-back system. The most expensive (and quietest) systems will also be the most restrictive; more affordable options are louder but still offer good noise suppression overall.

Type of Vehicle

The type of vehicle you drive can have a significant impact on what particular type of exhaust system is more beneficial. Sedans are generally better off with an axle-back system, while sport utility vehicles (SUVs) and pick-up trucks are almost always better off with a cat-back system.

Even then, however, your model may have special characteristics that alter the situation by requiring you to remove the catalytic converter for improved performance or include it in the exhaust system for noise level suppression.

Conclusion

In short, axle-back exhausts are designed to give a car a distinctive sound and performance boost. Cat-back exhausts provide more power but may not have the same unique “hum” as an axle-back does for those who want that particular noise quality.

If you’re ready to make your vehicle stand out from the pack or need help choosing between these two styles of exhaust system, feel free to contact us today! We can answer any questions you might have about your personal needs and preferences so we can recommend the perfect style of exhaust for you.