Ford Focus ST Build: How To Modify This Epic Hot Hatch

Introduction

Our Ford Focus ST Build is a riot of a car! Before the Focus ST arrived, the hot hatchback market was lacking in the United States. If you wanted a car with utility and good fuel economy but wanted a fun driving experience, your option was pretty much the Volkswagen GTI. Ford’s release of the Focus ST to the North American market provided an awesome driver’s experience at a great price. With the ST’s release came a solid aftermarket with the best upgrades for the Focus ST becoming quickly available.

I took advantage of Ford’s 0% financing and started my journey with a black Ford Focus ST. From my years of ownership and lessons learned through forums, I compiled a list of the best upgrades that transformed our Ford Focus ST build. In this guide, I will breakdown my favorite modifications, their cost, and what you actually gain from them.

Our Ford Focus ST Build

Rear Motor Mount

If I could only do one modification to the Ford Focus ST, it would definitely be the rear motor mount upgrade. The factory rear motor mount is soft and allows the engine to move a lot due to it not being able to handle the factory torque numbers. Switching to a stronger rear motor mount like a Mountune or CP-E will limit wheel hop at launch and improve your shifter feel.

Today, a rear motor mount will cost you between $150-$200 depending on brand. The modification itself took me about two hours to do, but most of that time was watching YouTube videos to make sure I was doing the install correctly. In stock form, the car’s torque steer is violent. However, once the rear motor mount upgrade was completed, I immediately noticed the reduction in motor movement and feeling a bit more grip up front when on the throttle.

Upgraded Front Mount Intercooler

The factory intercooler is decent, but is prone to heat soak. Unfortunately, this provides inconsistent power during spirited driving or track racing. Switching to an upgraded intercooler, even at stock power levels, provides much lower charge air temperatures. The lower temperatures provide consistent power and will also allow you to push the power levels further!

Personally, I went with a Mountune intercooler. I liked its performance and it came powdercoated black for a stealthy look! This modification will be instrumental when you tune the vehicle as it will allow you to maintain consistent power as you’ll mitigate heat soak. Our Ford Focus ST build had a Stratified off-the-shelf tune at first. However, once we found JST performance, a custom tune was needed. Without the upgraded intercooler, any further power gains would have been pointless.

Turboback Exhaust or Down Pipe Upgrade

Turbocharged cars like the Ford Focus ST love a free-flowing exhaust. While the factory catback exhaust is not restrictive, the downpipe provides a chokepoint for the Turbocharger. A downpipe upgrade, such as this 3″ downpipe upgrade from Depo, will let your Focus crank up the power levels. Should you elect to move forward with an aftermarket catback exhaust, I would find one with a quality muffler. Frankly, the car can drone pretty bad without a muffler, especially when you upgrade the downpipe.

For my car, I did a muffler delete with a high flow resonator. I loved it as it did not drone at all. Shoutout to Muffler Tech in Sacramento! If I were to buy a complete cat-back exhaust from a company, I would probably choose the AWE Touring exhaust. The touring exhaust sounds great in person and looks amazing.

The muffler delete and high flow resonator cost me approximately $300 back in 2016. A cat-back exhaust built by companies like CobB or MBRP can range from $500 to as much as $1000. Cost will mostly be dictated by the types of materials and construction used, but generally the 5-10 horsepower gain will be netted regardless of brand.

Cold Air Intake

If we’re trying to make horsepower, we definitely need to make sure we get enough air into the engine. A cold air intake brings in colder and denser air to help generate more power. While it won’t add more than 5 horsepower on its own, the combination of an exhaust upgrade, intake, and tune will really awaken the car.

Some Ford Focus ST builds get away with just a high performance air filter. However, after removing the factory intake and installing a Roush cold air intake, I felt the increased sound and cleaner look was worth the $300. Other intake systems will range between $200-$350 depending on brand. It is also a very simple modification to in your driveway and is definitely the car enthusiast’s modification rite-of-passage.

Cobb Accessport

With the addition of the turbo-back exhaust and the front mount intercooler, it’s time for power! With the Cobb Accessport and a tune from a reputable tuner like JST, the Focus ST will take advantage of these upgrades. Without the tune, the factory computer will more or less revert to stock power levels. For our Ford Focus ST build, we knew we wanted to take advantage of every dollar spent.

When I finished the tune, the power delivery was perfect. Along with the power upgrades, the data monitoring capabilities are great. The Accessport allows you to monitor inlet temperatures, boost levels, and more. All of this combined make this one of the best Ford Focus ST upgrades available. The Accessport alone is around $665 for the Ford Focus ST. In addition to the Accessport, a custom tune will be around $200-$250 depending on who you use.

With the Ford Focus ST build having an upgraded intercooler, modified exhaust, and a cold air intake, our initial custom tune was dyno’d on 91 octane. The JST performance tune netted us 251 wheel horsepower and 290 lb. ft of torque! Later down the road, JST provided us an E85/91 octane blend tune (E30), which really woke up the car! While it was never put on a dyno, it was clear we picked up a lot of torque and a bit more mid-range power.

Rear Sway Bar

Like many front wheel drive cars, the Focus ST leans towards understeer. Ford did engineer the car to try and mitigate understeer, but front-wheel drive physics are hard to overcome. To improve the handling, upgrade to a thicker rear sway bar! A thicker rear sway bar provides a more neutral handling feel and minimizes body roll.

The Focus ST has fantastic factory suspension, but I found the rear sway bar really made a difference. When I tested our Ford Focus ST build in an autocross track, I found the rear sway bar truly allowed the car to rotate flatter and not feel like I was trying to force it to corner. With a rear sway bar costing anywhere from $200-$300, it is a cost-effective mod for any front-wheel drive car!

My Ford Focus ST Build Sheet

• Muffler delete + High flow resonator
• Rally Innovations Front Splitter
• Perrin Shorty antenna
• ZL1 Rock Guards
• Anarchy motive Shift Knob
• Steeda Rear Sway Bar
• Steeda sound symposer delete
• Steeda Clutch Spring
• Steeda Short shift bracket
• Cobb Accessport
• Mountune recirculation valve
• Mountune rear motor mount
• Roush Cold Air Intake
• NGK Iridium IX spark plugs
• JST Performance custom tune https://jst-performance.com/collections/custom-tuning
• Mountune Intercooler
• Autostyle shift boot
• Diode Dynamics LED headlight bulbs
• TB Performance sway bar endlinks
• TB Performance Rear Traction Bar
• Enkei NT03 18×9.5 wheels
• BFGoodrich Sport Comp 2 Tires (245/40/18)
• Maxton Design RS Valence

Conclusion

Overall, these upgrades will transform your Focus ST without breaking the bank. While you can go build a big turbo motor, most people just want a bit more power and better handling. Fortunately, the Focus ST aftermarket has a huge aftermarket to fit any budget. If you have more questions about our Ford Focus ST build, feel free to reach out here or on our socials.

When modifying any car, consider planning out your goals. With my build, I definitely could have avoided wasting money on parts that I bought twice. Regardless of how you modify your Focus ST, you will not be disappointed!

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