Top 7 Best Ford Fiesta ST Modifications

When Ford released the Fiesta ST, automotive journalists and enthusiasts all over the world fell in love. Although it’s pretty slow in a straight line, the massive amounts of torque and quick spooling turbo make it feel much faster than it is.

When that’s combined with the brake-based torque vectoring system, rigid chassis, stiff suspension, and a 2,700 curb weight you end up with an insanely fun little car. If you’re serious about performance, however, a stock Fiesta ST might not cut it for you.

Luckily, there are a few modifications that will have a significant impact on the driving experience of your Fiesta ST for the better and help turn into a real performance car. We have hands-on experience with some of these Fiesta ST mods and know the massive difference they can make.

#1 Cold Air Intake

One of the best ways to let your turbocharged engine breathe is with a cold air intake. The stock system can limit the amount of air getting to the turbocharger, ultimately holding the engine back. A high flow filter is always a good option because the stock box is pretty good at pulling in cold, fresh air.

If you decide to ditch the stock system for an aftermarket unit, you will be rewarded with massive torque gains and a symphony of turbocharger noises. A cold air intake with a proper box or plating surrounding the filter will give you the most powerful, but a cheaper system like an Injen intake will still give you significant power gains.

Even with a muffler/resonator delete, you will be able to hear the turbo loud and clear from inside or outside the vehicle. It’s best to pair any modifications, including a simple intake update, with an aftermarket tune. Without tuning, the increase in airflow may not be fully capitalized on!

#2 Catback Exhaust

The ability to move exhaust gases faster and more freely results in faster turbo spooling and ultimately increased power. The stock Fiesta ST exhaust can be pretty restrictive especially if you have any other modifications. If you want to up the performance of your Fiesta, you can even throw an aftermarket downpipe into the mix, but just a catback system will result in big power gains.

The huge gains will be in the torque numbers thanks to Ford’s usage of the tiny KP39 turbocharger. The added exhaust sound will also transform the driving experience and make it much more engaging. Vivid Racing has catback systems ranging from $500 up to almost $900. Some have a quieter sound than others, and some use larger piping than others, but all of them will change the way your Fiesta ST feels behind the wheel.

It’s important to note that an aftermarket downpipe will further increase power gains, but the tiny OEM turbocharger is significantly limited and the gains from an aftermarket downpipe are relatively small compared to other turbocharged vehicles.

#3 Rear Motor Mount

Keeping a torquey little engine in place can be pretty difficult, and if you use very stiff engine mounts, you’ll end up with lots of vibrations in the cab. For this reason, Ford used fairly soft engine mounts to minimize cab vibrations, and the result is a lot of annoying engine movement. This movement can be felt through the chassis when downshifting and when launching from a standstill.

This problem is most noticeable when launching the car. During a hard launch with sticky tires, the engine moves so much that it bumps into the firewall. The result is a loud thunking noise. In addition to this thunking noise are wheel hop and wheel spin. Adding a stiffer rear engine mount alleviates all of these issues while adding a minimal amount of vibrations.

It’s important to not purchase an excessively stiff rear motor mount. Too stiff of a mount will result in a massive amount of cabin vibrations and will make your Fiesta ST rattle interior pieces.

#4 Intercooler

If you live in a hot climate such as Phoenix, Arizona, then this next modification is an absolute must. When you compress air, you increase its temperature, and if the air becomes too hot, it can cause detonation in your engine.

Not only will the hot air result in a power loss, but prolonged detonation can be detrimental to your engine. This problem is pretty severe in temperatures over 100F. For this reason, an aftermarket intercooler should be one of your first Fiesta ST mods.

An intercooler by itself won’t make any power gains. But it allows you to run more aggressive ignition timing and increased boost pressure without running into detonation. In addition to the intercooler, a set of aftermarket intercooler pipes will lower the pressure in the piping which allows the air to flow more freely which can improve power.

Again, this is a part that is best paired with an aftermarket tune, otherwise, the decrease charge air temperatures likely won’t be fully taken advantage of by your stock ECU tune!

#5 ECU Flash from VRTuned

If you want to squeeze the most power out your little 1.6L engine, then you’ll need an ECU tune. With a tune, you can increase ignition timing, increase boost, raise the rev limiter, eliminate torque limiting in 1st and 2nd gear, and more. Many people out there run a Cobb or Mountune AccessPort for their tuning, but Vivid Racing’s tuning division, VR Tuned, has a cheaper solution.

Coming in at $400, the VR Tuned ECU flash for the Fiesta ST is not only cheaper than the Cobb Accessport, but the tune file is also excellent. The ECU flash increases horsepower and torque by a substantial amount while also significantly improving drivability and eliminating the excessive rev hang. Plus, the VR Tuned ECU flash isn’t detectable, so you won’t have to worry about running into problems with warranty repairs.

Of course, similar tuning solutions such as the Cobb Accessport is still an excellent option. The important thing is just getting a quality tune of some kind on your Fiesta ST to get the most power from it possible.

#6 Coilovers or Lowering Springs

Although the stock Fiesta ST suspension is great for shredding canyons and dominating autocross events, the damping isn’t that great. This problem is most noticeable when on a bumpy road or highway. If you go on a long road time in your Fiesta ST, more than likely you’ll have a lot of back pain afterward because of how bumpy the ride quality is.

If you’re on a tight budget, you can pick up a set of lowering springs which will give a firmer ride and better stance, but the dampening problem will only be worse. The best way to make your Fiesta handle and ride better is with a proper set of coilovers. A good set of coilovers can provide a much higher spring rate for decreased body pitch and roll without making the ride quality any worse: This is because quality coilovers will be adequately dampened for the spring rates, unlike the stock struts.

Some coilovers will include separate height/preload adjustment and some may include damping adjustment. Features change based on the price, but more adjustments aren’t always better. With more adjustment possibilities comes the possibility of adjusting your suspension incorrectly. For this reason, sticking with a simple non-adjustable coilover may be the better option for many enthusiasts.

#7 Aftermarket Wheels

This last modification isn’t essential, but it’s the perfect way to make your Fiesta ST stand out. Unfortunately, Ford used a rather odd lug pattern which makes it hard to find wheels. Couple that with the small fender wells and you end up with a minimal selection of wheels. If you want something good looking that is specially designed for the Fiesta, a set of Fifteen52 wheels is perfect.

The Turbomacs are polarizing, and many enthusiasts don’t like them. Fifteen52 also offers the Tarmac which has a more simple design but will still give your Fiesta ST that rally-car look you want. There are a few other decent wheel options out there. Call us to talk with a sales rep to find and order the perfect set of wheels for you.

#8 Sticky Tires

Often tires are overlooked as a modification for your car because the performance benefits might seem minimal, and it’s not a modification you can brag about to your friends. At the end of the day, however, your tires are what’s holding your car to the road, and a quality tire will dramatically improve the driving experience of your Fiesta ST.

The OEM tires on the Fiesta are decent, but far from the best. The biggest problem with picking tires for a Fiesta is the limited size. The stock size is 205/40/r17, and going any larger than that can result in slight tire rub at full suspension bump or full steering lock unless you roll the fenders a little bit.

For the price, we like the Falken Azenis RT615K+ tires. They come in at a very reasonable price and provide excellent grip. More importantly, they are available in the OEM tire size which means you won’t have to worry about them rubbing on your fenders. Shop for all Fiesta ST tires by clicking here.

Ideally, increase your tire size to a 215/40/r17 is the best option for optimal grip and wear characteristics.

Summary

Although there are other awesome modifications like a big turbo upgrade, sway bars, seats, brakes, and more, we think these are the best bang-for-buck mods you can do. If you have any questions, please do not hesitate to contact us. We can be reached by phone at 1.480.966.3040 or via email at [email protected].