Should I Get an Axle-Back or a Cat-Back Exhaust System?

Almost all bolt-on aftermarket exhaust systems come in one of two configurations: the axle-back exhaust and the cat-back exhaust. There are many differences between these systems, and which one you should purchase depends on the goals for your upgrade. We’ve put together this guide to axle-back and cat-back exhaust systems to help you make the right choice when purchasing an MRT performance exhaust.

About the Exhaust System

Let’s start by talking briefly about exhaust systems. An aftermarket exhaust system typically replaces some or all the components from the catalytic converter to the rear bumper. The major components being replaced can include the exhaust tube, mid-pipes, exhaust tips and either a muffler or resonator. Which components you’re replacing have different effects on the vehicle. With this in mind, let’s get into how each type of exhaust system works.

What is an Axle-Back Exhaust System?

The axle-back exhaust starts at the rear bumper with the exhaust tips, then uses steel tubing to travel over or around the rear axle, encasing a muffler that attaches to the exhaust mid-pipes. Axle-back exhaust kits provide a rich, deep exhaust sound via muffler changes – such as Version 2 vs. Version 1 MRT systems for the Chevy Camaro, or the MRT King of the Hill vs. Trail-Rated axle-back for the Ford Bronco. You also get a “Look at Me” appearance modification via changes to the shape, diameter and/or color of the exhaust tip(s).

Axle-back exhausts are an affordable, lower-priced system for improved sound vs. factory systems. They’re also generally easier to install since there are fewer parts.

What is a Cat-Back Exhaust System?

A cat-back exhaust includes all the axle-back exhaust components, plus it replaces the OE mid-pipes. Sometimes it also adds a resonator or additional tubes to manage the drone resonance. Since the cat-back system replaces all exhaust tubing from the catalytic converters through the tips, they emit a deep, throaty sound.

Getting a cat-back performance exhaust provides the flexibility to match an axle-back system with different mid-pipe configurations, such as X-pipes or H-pipes, for different sound management. However, since there are more pieces, cat-backs cost more and are trickier to install.

Similarities Between Axle-Back and Cat-Back Systems

Although there are a lot of differences between these exhaust system configurations, they do have a few things in common. Both make sound, performance and appearance changes to a vehicle. Most aftermarket exhaust manufacturers increase the exhaust tube diameter and use mandrel bends in both types of systems to improve exhaust flow. These changes create gains in horsepower and fuel economy.

The amount of gain is proportionate to the exhaust change. The biggest performance gains come from the larger cat-back system. The smaller axle-back system produces smaller gains.

So Which Exhaust System Should I Get?

If your main interest is how your exhaust sounds and looks, get an MRT axle-back system for quick installation plus flexibility for future mods at an affordable price. If you want a “one-and-done” aftermarket exhaust to enjoy the deepest sound and added performance gains, get an MRT cat-back exhaust.