Quick answer
An axle-back replaces the muffler and tips behind the rear axle. It's the cheapest, easiest way to change your truck's sound. A cat-back replaces everything from the catalytic converter back, for a bigger change in sound and a little more flow. Both keep your factory converters, so they're legal in most states.
What each system replaces
- Axle-back: muffler (or muffler delete) and tailpipe/tips. Bolts on in under an hour on many trucks.
- Cat-back: mid-pipe, muffler and tailpipe from the back of the catalytic converter. More parts, more change.
- Header-back or turbo-back: goes further forward and may affect emissions parts. These have stricter rules.
Sound and drone
The muffler shapes most of the sound, so an axle-back can change the tone a lot. A cat-back adds a larger-diameter pipe and smoother bends for a deeper note. The thing most owners regret is drone: a low hum inside the cab at steady highway speed. If you drive long highway miles, choose a milder sound level or a system designed to cancel drone.
How the big brands differ
- Borla offers several sound levels for the same truck, from mild Touring to S-Type to aggressive ATAK, so you can pick your volume.
- MagnaFlow is known for straight-through stainless mufflers with a deep, classic tone, plus direct-fit catalytic converters.
- Corsa is known for strong sound outside with less drone inside the cab.
- BRExhaust makes direct-fit replacement kits that restore a rusted-out factory system.
Listen to the brand's sound clips for your exact truck and engine before you buy.
Will it add horsepower?
On most modern trucks, a cat-back adds a modest gain because the factory system already flows well. Bigger gains usually come with a tune. The real reasons to buy are sound, looks and stainless construction that outlasts the factory system.
Is it legal?
Cat-back and axle-back systems leave the catalytic converters in place, so they're legal in most states. Some areas enforce noise limits. Replacing catalytic converters has stricter rules, especially in California and states that follow its standards, so check the product's emissions notes.
Picking the right system
- Want a new sound on a budget? Axle-back.
- Want the full look and sound, plus stainless from the converter back? Cat-back.
- Long commute? A milder sound level, or a drone-cancelling design.
- Rusted-out factory pipes? A direct-fit replacement kit.
Shop all exhaust systems and mufflers, or see more performance parts.
Frequently asked questions
Is a cat-back worth it over an axle-back?
If you want the biggest change in sound and a full stainless system, yes. If you mainly want a new tone at a lower price, an axle-back gets you most of the way.
Do I need a tune with a cat-back?
No. Cat-back and axle-back systems work with the factory tune.
Will an aftermarket exhaust void my warranty?
In the US, a dealer must show that an aftermarket part caused a specific failure before denying a claim on that part. A cat-back is unlikely to affect unrelated systems.