Looking to improve the performance of your Mk3 Ford Focus ST? You’ve come to the right place.

The Mk3 Ford Focus ST is already a thrilling fast Ford straight from the factory. However, with the right modifications and tuning, its performance can be taken to new heights. In this comprehensive tuning guide, we’ll take you through various modifications and upgrades that will not only enhance the overall performance of your vehicle but also give it a unique and personalized touch. From engine upgrades and suspension tweaks, to advice on wheels and tires and styling tips, here’s our Ford Focus ST MK3 Tuning Guide. So, let’s dive in and unlock the true potential of your fast Ford!

Tuned Mk3 Ford Focus ST

Tuning the Mk3 Focus ST 2.0 EcoBoost Engine

The 2.0-litre EcoBoost has been with us since 2010. The standard 247bhp offers a lively drive, but it can be so much better with just a handful of tweaks. When it comes to enhancing the performance of your Mk3 Focus ST‘s 2.0 EcoBoost engine, there are several areas to look at. Our Focus ST Mk3 tuning guide looks at how upgrading the air filter, remapping the engine, adding a big turbo upgrade, and even considering forged engine internals can all make a huge difference in power output and driving experience.

2.0 EcoBoost engine in Mk3 Focus ST

First Steps: Air filter, Performance Exhaust, & Remap

To begin with, the basics of air filter, exhaust and remap will give 270-to-280bhp and really liven things up compared to the stock software.

One of the easiest and most effective ways to improve engine performance is by upgrading the air filter or intake system and a performance exhaust system. By increasing air flow into the engine, you can unlock additional power gains. Upgrading to a high-quality air filter allows for better filtration and increased air intake, resulting in improved engine performance.

Additionally, upgrading the exhaust system improves exhaust flow, reducing backpressure and allowing the engine to breathe more freely. This, in turn, can boost horsepower and torque, giving your Mk3 Focus ST a noticeable power increase.

Finally, an ECU remap is an essential part of maximizing power output in your Mk3 Focus ST. By modifying the ECU software that controls the engine, you can optimize the air-fuel mixture, boost levels, timing, and other parameters to achieve higher performance levels. Some popular tuning options include the Cobb Accessport, DreamScience iMap, and Mountune mTune, which allow pre-configured maps to be installed directly to the ECU. These also allow for the option of custom tuning too, where the specialist writes a file bespoke to your car which you can then upload at home.

Installing a performance intercooler

Further Tuning: Intercooler & Sports Cat

Another crucial component to consider when tuning your Mk3 Focus ST is the intercooler. The intercooler plays a vital role in keeping the intake air temperature down, allowing for denser air and more power output. Upgrading to a larger intercooler provides better heat dissipation, enabling higher boost levels and preventing power loss due to heat soak. Here are a few key points about intercooler upgrades:

  • Increased intercooler size allows for more efficient cooling of the intake air.
  • Reduced intake air temperature leads to higher power levels and improved performance.
  • Stock intercoolers are restricted in size, limiting their cooling capacity.

At the same time, you may want to consider swapping the original catalytic convertor for a high-flowing sports cat. The OEM cat can slow the exhaust gases from exiting the engine, causing increased back-pressure in the system. A free-flowing exhaust system allows for a better turbo spool, better throttle response, and ultimately higher peak power and peak torque figures.

Product shot of high performance engine internals on white background

Forged engine internals

The previously mentioned upgrades will see your ST kicking out around 300bhp. That’s more than enough for most and is arguably the sweet spot between power, performance, everyday reliability and cost. For more power, you really need to lay some stronger foundations in the shape of a fully-forged bottom end. It’s a wise idea given the fact the 2.0 has been known to suffer piston failure even at stock power. The jury is still out on exactly what causes the problem (weak components, LSPI, poor fuel, poor maintenance etc) but a set of forged pistons and uprated con-rods seems to sort the problem out.

These upgrades allow for higher boost levels and power output without the risk of engine failure. Forged engine internals are especially crucial for big power applications, where the engine is subjected to extreme levels of stress.

While the engine is stripped, it provides the perfect opportunity to install some performance camshafts too. The 2.0 EcoBoost cam profiles are quite mild, so fitting some performance cams is a great way to unlock more performance.

Modified Focus ST driving on a cobbled road

Turbo upgrades

With a bulletproof bottom end you can turn the wick up with a bigger turbo! By replacing the stock turbo with a bigger, high-performance turbo, you can achieve significantly higher power levels. Here are a few key points to consider when upgrading your turbo:

  • Upgraded turbos provide boost levels, resulting in great power output.
  • Bigger turbos offer improved flow capacity, allowing for higher power gains.
  • Compatibility with other performance modifications, such as intercoolers and intake systems, should be considered.
  • It’s important to ensure that the turbo upgrade is properly matched to your engine other components.

Fuel System

Like all Ford EcoBoost engines, the ST’s 2.0-liter version uses direct fuel injection technology. While there is certainly some scope to increase performance built into the OEM components, the stock fuel system starts to run out of juice at about 350bhp. Bigger injectors, however, are available and will see 400bhp. An uprated mechanical fuel pump may also be needed for further power gains. Alternatively, some tuners have added a secondary, supplementary port-injection fuel system to supply enough fuel for over 500bhp.

Modified Ford Focus ST Mk3 driving shot of the rear

Focus ST Mk3 Tuning Guide: Transmission Modifications

While engine tuning is essential for achieving higher power output, don’t overlook the importance of transmission modifications. That’s why this Focus ST Mk3 tuning guide looks at how upgrading components such as short shifter kits, and heavy-duty clutches, and adding a limited-slip differential can greatly improve the overall driving experience

Aerial shot of clutch plates with a white background

Clutch & Flywheel Upgrades

The stock clutch can cope with power outputs up to 300bhp. Heavy-duty upgrade kits are available, but using the clutch and dual-mass flywheel from the Mk3 Focus RS offers an OEM-quality upgrade that can easily handle most things an ST can throw at it. For hardcore drag and track users, race upgrades from specialists such as Xtreme Clutch are available if you really need them.

Aftermarket gearknob

Short Shifter Kits

Short shifter kits are a popular modification for improving the shifting performance of the Focus ST. These kits decrease the distance and effort required to shift gears, resulting in quicker and more precise shifts. They also enhance the overall feel of the transmission, making gear changes more responsive and engaging. Whether you’re a performance enthusiast or simply seeking an improved driving experience, a short shifter kit is definitely worth considering.

Quaife ATB being installed into a gearbox

Limited Slip Differentials

Limited slip differentials (LSDs) are a must-have upgrade for any serious performance enthusiast. By distributing power evenly between the front wheels, LSDs improve traction and reduce wheel spin during aggressive acceleration and cornering. This not only enhances the overall handling and stability of the Focus ST but also allows you to fully exploit its increased power output. Whether you plan on hitting the track or simply want to enjoy spirited drives on winding roads, upgrading to a limited-slip differential will undoubtedly take your driving experience to the next level. The most common upgrades include ATB types (Automatic Torque Biasing) from Quaife or Wavetrac.

Focus ST driving on a country road

Focus ST Mk3 Tuning Guide: Suspension Tuning

To complement the increased power output, it’s crucial to upgrade your Mk3 Focus ST’s suspension components. Suspension tuning plays a vital role in improving handling performance and overall driving dynamics. By upgrading components such as lowering springs, coilovers, and performance bushes, and optimizing the suspension alignment settings, you can significantly improve the handling of your Mk3 Focus ST.

Lowering Springs

Lowering springs are a popular choice for enthusiasts looking to improve both the performance and appearance of their Mk3 Focus ST. By lowering the car’s ride height, uprated lowering springs provide a lower center of gravity, resulting in improved handling and reduced body roll during cornering. They also offer a more aggressive stance and enhance the car’s overall aesthetics.

Coilovers: Should I fit them to my Focus ST?

Coilovers offer a higher level of adjustability compared to lowering springs, making them an excellent choice for those seeking a more customizable suspension setup. By combining a shock absorber and a coil spring into a single unit, coilovers allow for fine-tuning of the car’s ride height, damping, and rebound settings.

This level of adjustability enables you to optimize the suspension setup for different driving conditions, whether you’re on a spirited backroad drive or exploring the limits of your Mk3 Focus ST on the track. Additionally, coilovers provide improved handling, responsiveness, and a sportier feel compared to stock suspension. However, their race-inspired nature can make for a firm ride on the street. So, be prepared to compromise on ride quality for the benefit of adjustability. For purely street use, a set of matched springs and dampers like the Bilstein B12 kit is hard to beat.

Performance Bushes

Upgrading to performance bushes is another way to enhance the handling characteristics of your Mk3 Focus ST, which is why we’ve included them in our Focus ST Mk3 Tuning Guide. These bushes are designed to reduce chassis flex and provide improved responsiveness and steering precision. By reducing unwanted movement of suspension components, performance bushes help maintain proper suspension geometry, improving stability during high-speed manoeuvres. They also help minimize body roll, providing a more controlled and confident driving experience. Upgrading to performance bushes is a cost-effective way to upgrade your car’s handling performance without making major changes to the suspension system.

Alignment Settings

Proper alignment settings are essential for maintaining stability, predictable handling, and maximizing the performance of your Mk3 Focus ST. Alignment refers to the adjustment of various angles of the suspension components, such as camber, caster, and toe. Optimizing these settings can improve steering response, overall grip levels, and cornering performance. Correct alignment ensures even tire wear, reduces unwanted tire scrub, and provides optimal handling characteristics for spirited driving.

Focus RS with uprated brakesFocus ST Mk3 Tuning Guide: Brake Upgrades

Enhancing your Mk3 Focus ST’s braking performance is essential, especially when you’re pushing the car to its limits. Upgrading the stock brake system with high-performance components can improve stopping power, resistance to brake fade, and overall braking performance. Whether it’s upgrading brake pads, installing high-quality brake rotors, or considering big brake upgrade kits, optimizing your ST’s braking system will provide the confidence and control needed to handle higher power levels and enthusiastic street or occasional track driving.

EBC BlueStuff brake pads

Choosing the Right Brake Pads

Choosing the right brake pads is crucial when upgrading your Mk3 Focus ST’s braking performance. With the wide variety of brake pad compounds available, selecting the best one for your needs can make a noticeable difference in braking performance. For road use, it’s essential to choose brake pads that meet any local regulations, such as RC90 regulations for use on UK roads. Working hand in hand with other brake components, such as performance discs and brake lines, high-quality brake pads offer improved stopping power, fade resistance, and consistent performance.

Performance brake disc

Understanding the Importance of High-Quality Brake Rotors

High-quality brake rotors are essential components of an upgraded brake system and work in conjunction with performance brake pads to provide reliable and consistent stopping power. Upgraded brake discs offer several advantages over stock discs, including better cooling, improved performance, and reduced brake fade under demanding driving conditions. Whether you opt for drilled or slotted rotors, or even a combination of both, upgrading your brake rotors can significantly enhance your Mk3 Focus ST’s braking performance.

Tarox big brake kit

Big Brake Upgrade Kits

For those seeking the ultimate braking performance, big brake upgrades are a worthy consideration. An OEM upgrade is to use the 350mm discs and Brembo callipers from the Mk3 Ford Focus RS. These are a direct swap for the ST parts. Here are some key features of big brake upgrades:

  • Larger discs and more powerful calipers allow for increased stopping power and heat dissipation.
  • Upgraded brake pads provide improved performance and fade resistance under extreme conditions.
  • The complete system is designed to work together, ensuring optimal performance and safety.
  • While big brake upgrades can be more expensive compared to other brake upgrades, they are commonly found on serious performance cars and offer unmatched performance and reliability.

Aftermarket alloy wheels on Mk3 Focus ST

Focus ST Mk3 Tuning Guide: Wheel and Tire Modifications

Wheel and tire upgrades not only enhance the aesthetics of your Mk3 Focus ST but also play a crucial role in performance and handling. Choosing the right wheel and tire setup can greatly improve grip, responsiveness, and overall driving dynamics. Whether it’s selecting the right tires for performance driving or considering alloy wheel upgrades, these modifications will ensure that your car looks great and performs at its best on both the street and the track.

Selecting the Right Tires for Performance Driving

Selecting the right tires for your Mk3 Focus ST is essential to unleash its full performance potential. Equipping your Focus ST with high-performance tires ensures maximum grip, especially during spirited driving or on the track. Look for tires with a stickier compound and a tread pattern designed for aggressive driving. Fitting high-performance tires ensures maximum grip, especially during fast road driving or on the track.

Alloy Wheel Mods: What to Consider

The ST’s stock alloy wheels look good and are robust enough to withstand the vigors of daily driving. But that does come at a price, and that price is weight. Fitting lighter aftermarket alloy wheels reduces unsprung weight, improves responsiveness, and enhances the overall aesthetics of your Mk3 Focus ST. When considering alloy wheel upgrades, there are several factors to take into account, including:

  • Rim size, width, and offset: 19in diameter by 8.5in wide with an offset around ET45 is widely considered a fantastic setup for the Mk3 Focus ST
  • Weight savings: Lighter alloy wheels can reduce unsprung weight, improving suspension performance. Mountune’s OZ Racing Leggera HLT weighs in at just 9.9kg per wheel.
  • Durability and finish: High-quality alloys offer improved strength, durability, and resistance to corrosion.

Modified car interior

Focus ST Mk3 Tuning Guide: Interior Styling

Enhancing the interior of your Focus ST not only improves your driving experience but also adds a touch of personalization. Upgrading interior lighting, sound system components, floor mats, trim pieces, seats, and steering wheels are all great ways to enhance comfort, style, and functionality. Whether you’re looking for a more immersive audio experience, improved ergonomics, or a sportier feel, there are a number of interior styling options available to make your Mk3 Focus ST truly your own.

heavily modified Focus ST at a car show

Focus ST Mk3 Tuning Guide: Exterior Styling

When it comes to styling, there are several ways to make your Mk3 Focus ST stand out from the crowd. Companies like Delta Styling, Maxton Designs, and SS Tuning all have a wide selection of styling upgrades to choose from. From adding splitters and spoilers to upgrading headlights, taillights, or fog lights. Or customizing with decals or bespoke wraps, the possibilities are endless. With the right exterior styling modifications, you can make a statement wherever you go.

Press shot of Ford Focus ST

Inspired? Now looking to buy a Ford Focus ST?

If our Focus ST Mk3 tuning guide has inspired you, make sure you check out our Buyer’s Guide. Here, you’ll find top tips on what to look for and how much to pay for the best example available.