A cat-back exhaust kit usually includes new resonators, mid-pipes, mufflers, and exhaust tips that are smoother and
more direct than the stock system. The result is a more aggressive sound and better performance for your S550
But finding the right kit isn’t always easy due to the wide variety of options. To help you decide, we put together
this list of the best cat-back exhausts for 2015-2021 Mustangs.
Best for GT
The Roush cat-back exhaust for 2015-2017 GT Fastbacks is a top pick for delivering that signature Roush sound, look,
and performance. Polished stainless steel exhaust tips offer a modern style.
Another popular choice for ‘15-‘17 GTs is Borla’s famous “Stinger” S-type exhaust system. It’s compatible with
fastbacks and convertibles, bolting directly to the stock catalytic converters. The straight-through design
eliminates any exhaust drone.
For ‘18-‘21 S550 GTs, the Ford Performance by Borla cat-back exhaust is made for models that don’t have Active Exhaust. If you’re looking to really amp up the exhaust sound, this is the loudest option from Ford Performance’s
Best for EcoBoost
Cat-back exhausts can give your EcoBoost a louder, deeper exhaust note. The MBRP cat-back for S550 EcoBoosts without
the Active Exhaust is a great choice if you want to wake up your neighbors. Not only is it an aggressive-sounding
exhaust, but it also provides improved flow capacity for power gains.
You also can’t go wrong with the Borla ATAK cat-back exhaust. This system is acoustically tuned, and the Y-pipe
design eliminates the bulky factory resonator.
For a throatier exhaust note, the Roush cat-back system features mandrel bending for a higher flow and reduced backpressure.
Best for V6
Ford may have dropped the V6 engine from its lineup, but the aftermarket still provides plenty of cat-back exhaust
options. These Borla kits will give your V6 Mustang better power and sound.
The ATAK Cat-Back Exhaust is said to be the world's most aggressive system for 2015-2017 V6 Mustangs. The kit
includes a high-flow resonator that is lighter and less restrictive than the factory one.
If you’re looking for a mellower exhaust note, the Borla Touring cat-back exhaust offers a more controlled sound.
Borla’s S-Type cat-back system can give your V6 that deep, race-inspired rumble. The straight-through design helps
prevent exhaust drone as well.
Top Picks by S550 Owners
If you’re wondering what cat-back exhausts are popular with S550 owners, here are some of the top choices for both
the EcoBoost and GT.
If you’ve seen any of our YouTube videos, then you probably know that Bill is our resident Mustang expert. These are
some of his top picks for S550 cat-back exhausts.
For 2015-2017 GTs, Bill recommends the BBK Varitune cat-back exhaust. It features a patented adjustable power valve
that lets you tweak the exhaust flow through the mufflers’ chambers.
For ‘15-‘17 GT Fastbacks, Bill would go with the MBRP Aluminized Series Race cat-back exhaust. It uses an H-pipe
design for an old-school muscle car sound.
Bill’s pick for 2018-2021 GTs without Active Exhaust is AWE’s Track Edition exhaust. It has a clean, straight-through
design that offers a raw, track-inspired sound. This exhaust is for fastbacks only, as they will not fit the
Best Power Boost
The AWE Track Edition cat-back exhaust for ‘15-‘17 GT Fastbacks provides a power boost by using a non-baffled,
straight-through design. It has an H-pipe assembly with two bullet-style resonators. It’s designed to be one of the
loudest exhausts out there. AWE estimates max gains of 8 hp and 18 lb.-ft. of torque.
2018-2021 GTs without the factory Active Exhaust can improve airflow and reduce backpressure with the Roush 422093
cat-back exhaust system. It also offers a high-performance sound to match.
Another good option for these Mustangs is the MBRP Pro-Series Race cat-back exhaust. It uses an H-pipe with
mandrel-bent stainless steel tubing that is both larger and lighter than the stock exhaust.
When it comes to performance mods, you usually get what you pay for. But these cat-back exhausts offer a good
combination of both value and performance.
Mods to Pair with Your New Cat-Back Exhaust
Cat-back exhausts go great with other mods, especially a cold air intake and a tune. If you already have a cold air
intake and are installing a cat-back exhaust, tuning can help optimize the performance. It’ll adjust the air-fuel
ratios, fuel economy, and other settings so you can achieve the best performance possible.
If these are still out of your price range, an axle-back kit is a more affordable option if you're mainly focused on
improving your exhaust's sound. Sign up for
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This article was researched, written, edited, and reviewed following the steps outlined in our editorial process. Learn more about CJ's editorial standards and guidelines.