Best Ford S550 Mustang Mods Guide

From 2015–2023, the S550 Ford Mustang was the consummate modern pony car. Featuring either a turbocharged 2.3 liter “EcoBoost” inline-four or a naturally aspirated 5.0 liter “Coyote” V8, the S550 Mustang was one of the top power plants for the American market for many years. Still, even with the 310+ horsepower from the EcoBoost and the 435+horsepower from the Coyote, some feel it still leaves a bit to be desired compared to the even more powerful Shelby series, or the rival SRT Series of the Dodge Challenger and Charger. That’s why today we’re looking at the top S550 Mustang mods for performance increases. We’ll start with modifying the engine and then look at how to build the suspension to handle it. Read on to find out the top S550 mods for your 2015+ Mustang. 

Ford S550 Mustang Engine and Suspension Basics

The S550 is the sixth generation of the Ford Mustang, and Ford produced it for the 2015–2023 model years. During its run, Ford gave the S550 Mustang and Mustang GT three different power plants. In addition, the 2015 Mustang was the first to have independent rear suspension as standard on every model, from the base up to the GT. Many people consider the S550 Mustang to be the best Mustang ever produced. 

From 2015–2017, the lowest tier option used a naturally aspirated 3.7 liter “Cyclone” V6, which produced 300 horsepower and 280 lb-ft of torque. However, Ford dropped the engine for the 2018+ model year. Above the Cyclone V6 was the turbocharged 2.3 liter “EcoBoost” inline-four. It output 310 horsepower and 320-350 lb-ft of torque, which bumps it to 330 horsepower with the high performance package. 

The top-tier Mustang GT used the same 5.0 liter “Coyote” V8 for every year, but power output bumped up considerably. From 2015–2017, the Mustang GT made 435 horsepower, which jumped to 460 horsepower from 2018–2021. The S550 Mustang GT ended life from 2022–2023 with a 450 horsepower Coyote V8, which dropped slightly due to new ratings. Ford also used the 5.0 Coyote inside the Bullitt and Mach-1 variants, where it made 480–470 horsepower. 

Top Ford S550 Mustang Mods

Our top S550 Mustang mods are:

• Tune
• Cold Air Intake
• Exhaust
• IRS Subframe Braces

Regardless of your engine platform there are several must-do S550 Mustang upgrades if you’re looking to increase performance. First up is ECU tuning. This applies to all three engines, the Cyclone, EcoBoost, and Coyote, and is by far the biggest bang for your buck. Tuning can net 10-20% increases in power without any bolt-on modifications, and installation is extremely simple. 

After tuning, the next S550 Mustang mods we suggest are improving the airflow by upgrading both the intake and the exhaust. Adding a cold air intake is a no-brainer modification that will lower intake temperatures, increase horsepower and airflow, and make the engine bay look much improved. Cold air intakes are probably the most popular S550 Mustang mod, and for good reason.

For exhaust upgrades, there are many different ways you can go. For the turbocharged EcoBoost I4, upgrading the downpipe is the best way to improve exhaust flow and reduce restriction. On the naturally aspirated Coyote V8 and Cyclone V6, you’ll want to look at either short-tube or long-tube headers to get the biggest performance bump. On the V6 and V8 you can also look at x-pipes and h-pipes. These delete the resonator and are more for adding volume than power, but they are also very popular. 

The final exhaust options are to upgrade either the axle-back or the full cat-back. The cat-back attaches to either the downpipe (in the EcoBoost) or the headers (in the Coyote/Cyclone), and the axle-back is the muffler portion of the cat-back. Both of these are similar to an x or h-pipe upgrade, in that they add sound rather than power. 

Suspension Upgrades

Finally, we suggest upgrading the independent rear suspension (IRS) braces to make it stiffer. Unfortunately, the S550 suffers from excessive wheel-hop and poor spring deflection. While there are literally dozens of suspension upgrades to curb this, by far the best is the subframe brace. The IRS subframe support brace keeps the car much more locked together to prevent any moving twisting or vibrating that hurts handling. 

1) Ford Mustang ECU Tuning

For our first Mustang S550 mods, we suggest going with ECU Tuning. ECU tuning is available for all three of the Mustang’s engines, and it is by far the most cost effective mod for gaining horsepower and torque. Flash ECU tuning involves installing an aftermarket tune onto your car’s engine control unit (ECU) which replaces the stock programming.

Compared with stock, an aftermarket tune will boost horsepower and torque, improve the power band, improve the throttle mapping, and sometimes even increase gas mileage. Tunes accomplish this through increasing things like fuel pressure and advancing the ignition timing, and in the case of the EcoBoost: jacking up the boost pressure.

Flash tunes are incredibly easy to install, and give you immediate gains without requiring any bolt-on modifications under the hood. Additionally, if you have bolt-on mods, like an upgraded intake or exhaust, tuning will help your engine get even more power out of them. No question, tuning should be the first of your Mustang S550 mods. 

Best S550 Mustang Tuners

For the S550 Mustang, there are a lot of different choices for tuning the EcoBoost and Coyote. For the Cyclone V6 Mustang, your options are a bit more limited, but we recommend Auto Mafia Racing Mustang V6 Tuning. They offer custom tuning for Cyclone Mustangs through email, and use the SCT flashing device. 

For the EcoBoost mustang, we recommend Livernois Motorsports. They tune all years of the 2.3 Mustang, and they deliver some incredible power gains. On 93 octane with just tuning, Livernois Motorsports claims gains of more than 60 horsepower and 100 lb-ft of torque. That’s pretty incredible, and is done through custom email tuning and Livernois proprietary MyCal handheld tuner. They offer both 2015-2017 Livernois Motorsports Mustang EcoBoost Tuning and 2018+ Livernois Motorsports Mustang EcoBoost Tuning.

For the Mustang GT, we also recommend Livernois Motorsports tuning. Just like on the EcoBoost, they offer some serious gains. It’s not quite as much as the EcoBoost, but with the 5.0 Coyote they claim gains of more than 40 horsepower and torque with just tuning. Like the EcoBoost, they offer both 2015-2017 Livernois Motorsports Mustang GT Tuning and 2018+ Livernois Motorsports Mustang GT Tuning. In addition, Lund Racing Mustang GT Tuning is another very popular alternative for all years of the Coyote Mustang. 

2) Ford S550 Cold Air Intake Upgrade

Next up for the top S550 Mustang mods we have an upgraded cold air intake. Cold air intakes are one of the most popular S550 Mustang mods available, and it seems like pretty much every build starts off with one. It’s worth noting, that the OEM intakes are actually considered “cold air intakes,” because the filter is routed well away from the engine towards the fender. 

Aftermarket intakes real benefit comes from being larger and less restrictive than the stock intake. This means they can suck in and deliver more air to the engine, which means more horsepower and torque. In addition, usually cold air intakes use materials that are less conducive to heat soak. This can lower intake temperatures, again resulting in more horsepower. 

Intakes work a little differently on naturally aspirated vs turbocharged cars. On a naturally aspirated engine, they feed the throttle body which then feeds the engine. On a turbocharged car, the intake feeds the turbocharger directly. This makes intakes more beneficial on a naturally aspirated car, because the EcoBoost uses an intercooler, which is way more effective at reducing intake temperatures. Naturally aspirated engines do not use intercoolers, so the colder air the intake can grab the better.

Best S550 Mustang Intakes

For the S550 Mustang, we recommend the Roush Performance intake for all three engines. Roush is one of the most recognizable names in the aftermarket Mustang community, and their intakes are well engineered and look fantastic. 

The Roush S550 3.7 Cyclone cold air intake is for the 2015–2017 V6 Mustang, is CARB legal, and adds ~10 horsepower and torque. For the EcoBoost, there is the Roush S550 2.3 EcoBoost 2015–2017 cold air intake and the Roush S550 2.3 EcoBoost 2018+ cold air intake. These are also CARB legal as well, but add even more performance, closer to 30 horsepower and torque, according to Roush.

Finally, there is the Roush S550 5.0 Coyote 2015–2017 cold air intake and the Roush S550 5.0 Coyote 2018+ cold air intake for the Mustang GT. These kits are not CARB approved, but add around 10 horsepower and torque. You can’t go wrong with any of the Roush intake kits, and they are all proven performers. 

3) S550 Downpipe or Long-tube Headers Upgrades

Next up for our S550 Mustang mods recommendations, we’re looking at downpipes and long-tube headers to upgrade the exhaust. Downpipes work with turbocharged systems, like the EcoBoost, while long-tubes work with naturally aspirated systems, like the Cyclone and Coyote. While they look and work slightly differently, they both have the same purpose: reduce exhaust back pressure and improve flow. 

On the EcoBoost, the downpipe connects directly to the turbocharger. It works through the wastegate, which flows excessive exhaust gasses away from the turbo and into the downpipe once the desired boost level is reached. On a naturally aspirated engine, the long-tube headers connect directly to the exhaust side of the cylinder heads. They take in all of the exhaust gasses exiting the engine, and push them through the rest of the exhaust.

On both systems, an aftermarket downpipe or headers will reduce restriction and back pressure, increasing the exhaust flow and volume. This is primarily done through replacing or removing the catalytic converter and using larger diameter piping. Upgraded downpipes and headers allow for better scavenging, or replacing the dirty air with clean air, which is incredibly beneficial for performance. Basically, the purpose of the exhaust is to remove spent gasses out of the engine as quickly as possible. Aftermarket downpipes and long-tube headers do exactly that.

They come in both high-flow catted or catless versions. For those using their cars on the street, we suggest staying with the catted versions. For off-road or race vehicles, going catless will add another 5-10 horsepower on top of a catted exhaust. 

Other Exhaust Upgrades

Additionally, there are also X-pipe, H-pipe, cat-back, and axle-back exhaust upgrades. The cat-back connects directly to the downpipe or long-tube headers. The X-pipe and H-pipe are the middle part of a naturally aspirated exhaust. They usually contain the resonators and not catalytic converters. Upgrading the X or H-pipe will result in a louder and more raspy exhaust sound, but won’t add very much performance.

The cat-back is connected to the downpipe on a turbocharged car, and includes the exhaust back through the mufflers. On a naturally aspirated car, the cat-back connects directly to the headers, and contains the X/H-pipe. The axle-back is the muffler portion of the cat-back. Upgrading the cat-back and axle-back is mostly done for sound, as they do not add much performance. 

Best S550 Mustang Exhausts

Starting with the Cyclone V6, the best exhaust is the BBK Performance Mustang V6 long-tube headers. These will add about 10 horsepower and torque, and are 1 ¾ inch diameter, which is much bigger than stock. For the Coyote V8, we suggest the American Racing Headers Mustang GT long-tube headers. These contain the X-pipe and can be as wide as 2 inches in diameter. Finally, for the EcoBoost I4, we suggest the CVFab Mustang EcoBoost catted downpipe. CV also offers a catless version, too.

For Cyclone and Coyote Mustang owners, we suggest listening to different sound clips and making your own determination. Like we mentioned, cat-backs and axle-backs won’t really add performance and are really only for sound, so make sure you get something you like.

4) S550 IRS Braces for Independent Rear Suspension

For our final S550 Mustang mods, we suggest improving the independent rear suspension, or IRS. The S550 was the first Mustang since the 2003–2004 Cobra to get IRS, and while it adds a ton of performance, it can also struggle to put down all of the Mustang’s power to the pavement.

Basically, the extreme amount of torque the S550 Mustangs create can cause the suspension to twist, vibrate, or move in ways that are unintended. This can result in things like wheel hop and spring deflection, which ruin the driving experience. Installing IRS support braces will help keep the car’s suspension locked together under extreme driving. This will help the car handle much better, launch better, and put down all the glorious power down to the pavement. 

Best S550 IRS Braces

Our recommendation for improving the IRS is the Steeda IRS subframe support brace. The Steeda braces does an excellent job of locking the car together under tough driving situations, and really transforms the handling to make it much more crisp and locked together. 

In addition, there is also the Steeda S550 Stop the Hop starter kit, which also includes subframe bushings and an alignment kit. All three together, the braces, bushings, and alignment kit, should eliminate all wheel hop and let the Mustang perform as it should when being pushed to its limits. The IRS braces fit all versions of the S550 except convertible, and work with the Cyclone, Coyote, and EcoBoost engines. 

Top S550 Mustang Mods FAQ