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What’s the Difference Between a Catback Exhaust and an Axle-Back Exhaust on an S550?

What’s the Difference Between a Catback Exhaust and an Axle-Back Exhaust on an S550?

Ford decided to change up the Mustang's exhaust for the S550. Swapping out the stock pipes for a cat-back or an axle-back is a bit different from what you might be used to. One thing is for sure. The stock pipes are too quiet to show off the S550 Mustang's power.

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An exhaust system can change the entire attitude of your ride. Although the 2015 has seen some drastic changes to the piping, the aftermarket is prepared.

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What’s the Difference?

When it comes to change the exhaust note on your S550 Mustang, there are a couple different choices. The two most popular exhaust modifications are axle-backs and catbacks. Both offer a great way to give your Mustang the deep rumble that a factory system can’t, but they do it a little bit differently. An axle-back works by replacing just the mufflers on your Mustang. They get their name because they replace the exhaust pipes from the axle, back. The catback replaces your exhaust from the catalytic converters back, including the mufflers.

Which One Should I Choose?

If you are satisfied with the power level of your S550 Mustang, the best choice for you would be an axle-back system for your Mustang. They are more economical than a catback, and will give you a more aggressive exhaust note. The only downside to the axle-back is that it does not improve your exhaust flow, is a purely a sound mod. If you want to improve your exhaust flow without adding expensive headers or removing your catalytic converters, a catback is going to give you the flow you want, along with a better exhaust note.

S550 Mustang

Benefits to an Axle-Back Compared to a Catback System

An axle-back is an easy way to give your Mustang some extra growl without breaking the bank. They are cheaper than a complete catback, and perfect for someone looking to get a more aggressive sound without spending a ton of money. You will have to cut the stock exhaust to install one, but this is a simple install for any DIY Mustang owner. Just use the included template, and you’ll be good to go! The awesome sound is worth taking a saw to your pony!

S550 Magnaflow Axle-Back

Benefits to a Catback Compared to an Axle-Back System

In order to keep the volume at a reasonable level, Ford installed a large resonator on the stock exhaust, right after the cats. This resonator is heavy, restrictive, and it hinders performance. By installing a catback you will be deleting the bulky stock resonator with a free flowing X or H pipe. A catback  will also allow you to drop about 25-30 pounds off your Mustang. The extra horsepower and weight savings will improve the performance of your Mustang, along with the tone.

Mac S550 x Pipe


If you are shopping for a new exhaust for you 2015 Mustang, I would recommend a catback. The performance increase, the weight savings, and the more aggressive tone are all worth the extra cost of the catback. If you own a V6 2015, you will have to stick with an axle back since there are no catbacks available for the V6. Convertible owners also can not install a catback, since the exhaust tubing is not compatible with the convertible bracing. The only way to install a catback on a convertible is to remove the factory bracing, giving up some of that added stiffness. Another bonus for the catback is that there is no cutting required. The factory catback just unbolts, and the new one bolts in place. The axle-back will require you to cut the stock mufflers off and clamp the new ones on. No matter which set up you choose, anything is better than the quiet factory exhaust!

Benefits of a Catback

  • 20-30 pounds weight reduction
  • Better exhaust flow
  • More aggressive exhaust note and increased exhaust volume
  • 25-30 RWHP gain over stock catback

VIDEO: The 3 Best Cat-Back Exhausts for the EcoBoost Mustang

Benefits of an Axle-back

  • Increased exhaust volume 
  • More aggressive exhaust note
  • Less expensive compared to a catback
Ecoboost Axle-Back
Fitment includes: 2015, 2016, 2017, 2018, 2019, GT, V6, EcoBoost, ShelbyGT350