The 5 Best Ford Focus ST Performance Mods

Produced from 2012 until 2018, the Ford Focus ST was equipped from the factory with the 2.0L I4 EcoBoost. As one of the smaller engines in the EcoBoost family, the 2.0 doesn’t always get the credit it deserves thanks to the 2.3L, 2.7L, and 3.5L versions which outsize and outpower the Focus ST’s engine.

The 2.0 turbo engine in the Focus ST produces 252hp and 270lb-ft. of torque bone stock. Fortunately, the turbocharged design allows for significant power gains with just a few bolt-on mods. The Focus ST is capable of 300+whp with the performance upgrades we discuss in this guide.

Best Ford Focus ST Engine Mods

• Flash Tuner
• Performance Intake
• Downpipes
• Intercooler (FMIC)
• E85 Fueling

With respect to performance gains, ST’s with the 2nd Gen 2.0 EcoBoost will produce around 15whp more than 1st Gen’s due to the design changes Ford made.

If you would rather consume this content via a video, check out our How to Build a 300+ WHP Focus ST video below:

1. Flash Tuner

A flash tuner is one of the best modifications for a Focus ST because it offers the best bang-for-the-buck. Additionally, a tune is the foundation for further modification. When combined with the other mods on this list a tune can add up to 50whp and 70wtq.

We consider tunes the foundation to mods because without a proper tune the other mods on this list won’t offer their maximum benefit. Tunes adjust the fueling, AFRs, boost targets, etc. based on the other modifications on the car to maximize the power gains from the additional upgrades.

While custom tuning or dyno tuning is an option, we recommend starting with a flash tune. Every time you further modify your car you will need to have it re-tuned if you opt for custom tuning. On the other hand, flash tunes auto adjust when other upgrades are added and also come with a range of different prebuilt tunes. Custom tuning still requires a flash tuner as well unless you are getting it dyno tuned.

Tuner Price: $350-$550

Focus ST Tune Power Gains: 20-50whp and 30-70wtq

2. Cold Air Intake

An upgraded intake probably comes second on our list for best first mods, after a tune. Tunes primarily make more power by increasing the amount of boost that the turbo is running. Increasing boost requires more airflow. The stock intake is pretty good from the factory and usually won’t cause any issues for a Focus ST running a modest tune. However, once you begin running a more aggressive tune and further modify your engine the stock intake starts to become restrictive.

Since the stock system is pretty decent, you should only expect to get ~5whp from an intake on a stock ST with a modest tune. However, once you add the additional mods on this list and a more aggressive tune those gains can increase to about ~10whp.

The additional benefit of a tune is that it makes the turbo more efficient which makes it more reliable. The more air you bring into the engine the less work the turbo has to do pressurize it which takes stress off of it, increasing horsepower and reliability.

Focus ST Cold Air Intake Benefits

• 3-10whp and similar torque gains
• 40%+ increases to airflow
• Faster turbo spool and greater turbo efficiency
• Cool intake and turbo sounds

3. High-Flow Downpipe

Downpipes are unique to turbocharged engines and are the first component of the exhaust system in turbo cars. The downpipe connects directly to the turbo and also houses the primary catalytic converter. Since the downpipe is catted it is highly restrictive. This restriction creates a lot of backpressure for the turbo which reduces turbo efficiency.

The stock downpipe is great for emissions but bad for performance. You want the least amount of backpressure possible behind the turbo which is why upgrading your downpipe is a fantastic performance mod. Outside of producing power gains it also improves turbo reliability.

For a more in-depth downpipe guide, checkout our Focus ST Downpipe Guide.

Upgraded Downpipe Benefits

• 5-15whp gains
• 10-20wtq gains
• Faster turbo spool
• Improved turbo efficiency and reliability
• Slightly louder exhaust note (not as obnoxious as a cat-back)

Less backpressure creates lower exhaust gas temps and reduces the stress on the turbocharger allowing it to spool more quickly. You might read on forums or other blogs that you should upgrade your cat-back exhaust system and that the downpipe doesn’t matter as much. This is completely false. Virtually all of the exhaust backpressure is created by the downpipe which is why it offers such great power gains.

Don’t expect to get anywhere near these level of power gains with a cat-back or even full exhaust system unless you also upgrade the downpipe.

CVFab High-Flow Downpipe

CV Fabrication offers our favorite Focus ST downpipe on the market. Just over the $400 price point makes it one of the best bang-for-the-buck high-flow downpipes on the market. The CVFab downpipe is a 3″ stainless steel downpipe. It offers great fitment and just as much quality as the other more expensive brands on the market.

Price: $425

Buy Here: CVFab Focus ST High-Flow Downpipe

4. Intercooler (FMIC) Upgrades

Front mount intercoolers are not only important for performance but also extremely important for reliability. Intercoolers don’t provide the biggest power gains but instead provide more consistent power delivery and healthier engine temps.

The stock intercooler is effective on the stock engine but once you add a tune and increase boost it quickly becomes overwhelmed. The stock intercooler begins to experience heat soak where it cannot efficiently cool the large amounts of air before entering the engine. The end result is passing a lot of hot air into the combustion chamber.

Hot air is less dense and causes the engine to pull timing to prevent misfires and pre-detonation issues. When you are consistently hitting the throttle, whether just driving aggressively on the streets or during track days heat soak can can cause you to start losing power quickly. On the stock intercooler you can lose about 20whp when the intercooler is experiencing a lot of heat soak.

An upgraded intercooler will add about 5-10whp but will also prevent the engine from losing power during aggressive driving.

Upgraded Intercooler Benefits

• 5-10whp gains and similar torque gains
• Lower intake air temps
• Consistent performance through heat soak reduction
• Lower chances of misfires or pre-detonation

CVF Street Intercooler

As is with downpipes, CVFab offers our favorite intercooler on the market. At $500 it is one of the best combinations of quality, performance, and price. The street intercooler is 115% larger than the stock intercooler for maximum cooling capabilities. Street testing shows a decrease in intake air temps by 41 degrees over the stock intercooler. Additionally, the huge intercooler core allows for up to 670whp which can support just about any aggressive Focus ST build.

Additionally, if you’re looking for better airflow we recommend combining the CVF street intercooler with an intercooler piping kit. The piping kit includes both the cold side chargepipe and the hot side piping, which are both very restrictive from the factory. This will improve airflow from the turbo to the intercooler and from the intercooler to the engine. You can also opt for a chargepipe with an HKS flange so that you can add an HKS SSQV blow-off valve for cool sounds.

Price: $499 (intercooler) + $320 (piping kit – optional)

Buy Here: CVF Focus ST Street Intercooler and Intercooler Piping Kit

5. E85 Fueling

First of all, make sure you are running 91 or 93 octane if you are tuned. Higher octane allows for better timing and reduces the chances of engine knock. While race gas is an alternative option it is very expensive and not always readily available. Therefore, the best option for the Focus ST is E85 ethanol fuel.

The stock fueling system on the 2.0 EcoBoost can handle a blend of E85. While running 100% E85 will require some fueling upgrades, you can safely run an E30 blend with the proper tune.

Ethanol or E85 has an octane rating of 108. Additionally, it burns cooler and cleaner than traditional gasoline which allows for more aggressive timing and more boost. Running an E30 blend with a proper ethanol tune can add 10-15whp to the Focus ST.

Power gains are even higher when you run 100% E85 especially alongside an upgraded turbo but this will require fuel pump upgrades, port injection, etc.

E85 Fuel Benefits

• 10-15whp and similar torque gains
• Allows for more aggressive timing
• Allows for more boost
• E85 is cheaper than pump gas

An additional alternative to running E85 is using methanol injection. However, this requires a standalone methanol injection kit and is a more advanced fueling mod that we won’t go into depth about in this guide.

6. Ford Focus Motor Mounts

This is a bonus Focus ST upgrade that we recommend to all owners who are adding additional power to their 2.0L Focus engines. The Focus ST engine shakes a lot. This creates a lot of wheel hop and bounciness between gears.

The stock motor mounts are way too soft which allows the engine to shake too much. When you throw mods and extra power at the ST it makes the engine shake even more resulting in more wheel hop. This causes less power to get sent to the ground and ultimately makes your car feel slower than it should under hard acceleration. It also makes the car a bit more difficult to control under acceleration.

Stiffer motor mounts cost about $150 and will help provide way better traction and grip on the road when you want to floor it.

Ford Focus ST Power Potential

We consider the 5 mods listed here to be “full bolt-on”. While there are additional mods you can perform like a full exhaust system, an intake manifold spacer, etc. we left these off the list as these mods don’t provide enough power gains to justify the costs. With only these mods mentioned, your Focus ST will produce 300-320whp and 340-360wtq. Considering all of these mods can be made for sub $2,000 makes the Ford Focus ST a very mod-friendly car.

While the 2.0 EcoBoost can handle more power getting to those levels will require an upgraded turbo, advanced fueling mods, and eventually internal upgrades.

Ford underrated the Focus ST power numbers from the factory with bone stock cars dyno’ing in the 240-250whp range. These 5 mods will get you to 300-320whp meaning you can achieve up to 80whp gains for less than $2,000 in mods. Keep in mind the differences between the 1st gen and 2nd gen EcoBoost engines. First gen engines will likely be on the lower end of all the quoted figures.