Ford Fiesta ST Tuning And Modification Guide

Ford Fiesta ST Modification Guide

The Ford Fiesta ST is one of my favorite cars currently on sale in America. It’s just such a great package for a great price, and it puts most other cheap performance cars on sale in America to shame. If your budget is a strict $25,000 and you want a fun new car, you’d be a bit foolish to buy anything else.

Of course, with any performance-focused car, owners want to know how they can make their car faster with aftermarket parts and tuning. I thought the Ford Fiesta ST had pretty much everything going for it in stock form, but it’s only human nature to want to push things further.

A friend of mine just got himself a Ford Fiesta ST, and that has inspired me to write this overview on modifications and tuning for the car. Now, The Smoking Tire has already done some wonderful videos on upgrading their Fiesta ST. Because I want you, the reader, to have the best information available here, I will include those videos in this post. Also, see the table at the bottom for all the numbers in one place.

Let’s get to it!

Ford Fiesta ST Stock — 204bhp and 236ft/lbs

Honestly, there isn’t anything that this car “needs” added in terms of performance. It is a spritely little bugger out of the box, and most drivers will be happy with it as-is.

Ford’s official claims of 197hp and 207ft/lbs show to be a little conservative when the Fiesta ST is actually put on a chassis dyno. The numbers above are more realistic.

You should know up front that the factory tune on the Fiesta ST is already pretty aggressive. There isn’t too much room left for major gains with the stock turbo. Then again, a stock Fiesta ST already has trouble putting its power down without spinning the wheels, so huge gains may not be desirable in a little car like this for many folks. The Fiesta ST also only weighs around 2700lbs, so the power left in the stock turbo will go further for the experience.

Ford Fiesta ST Stage 1 — 208bhp and 248ft/lbs

Stage 1 consists of an ECU flash/tune and a drop-in panel air filter. Largely because the stock tune is already pretty aggressive, Stage 1 power and torque gains are very marginal. The Stage 1 tune will smooth out the power curve a little, but personally I wouldn’t bother. A few hundred dollars is a lot of money to get very little, so my advice would be to keep saving up for Stage 2.

Ford Fiesta ST Stage 2 — 234bhp and 302ft/lbs

Stage 2 consists of a cold air intake, a larger intercooler and the tune to go with them. It also includes a more robust rear engine mount, because the stock one likes to let the engine tap the firewall.

In plain terms, I see Stage 2 as the way to go if you plan to lightly upgrade your Fiesta ST. Stage 2 gives you the most gains per dollar. The extra grand or so that you’d spend for Stage 3 just doesn’t seem worth it for only a tiny bit more power.

For the OCD people out there, Stage 2 will get you to the all-important 200whp mark.

Ford Fiesta ST Stage 3 — 241bhp and 319ft/lbs

Stage 3 adds a turbo-back exhaust to what you get with stage 2.

Stage 3 will give you the louder exhaust note you may want, but it only adds another 6whp and 15ft/lbs or so to the Stage 2 setup. At more than a grand over a Stage 2 setup, it really isn’t worth it unless you absolutely need the louder sound in your life.

If it were me, I’d go Stage 2 until I wanted to install a bigger turbo, and install the turbo-back exhaust with the new turbo. The Fiesta seems to run out of air, fuel, or probably both around Stage 2. A bigger turbo is necessary for owners wanting more than just marginal horsepower gains.

Ford Fiesta ST Turbo Upgrade — 280bhp+ and 330ft/lbs+

For those of you who don’t feel you have enough torque steer with a 240hp Fiesta ST, a turbo upgrade may be just what the doctor ordered. And might I recommend some much wider wheels and tires at this point.

There are already a few turbo kits out there for the Fiesta ST. 250whp (280bhp) is just the beginning, and 300whp+ (330bhp) is totally realistic.

Personally, I would never want over 300whp in a tiny, front-drive car like a Fiesta ST, but I’m glad it’s been do-able.

Here is a table with all of the numbers in one place. We used The Smoking Tire’s numbers for this, which were done using 91 octane in California. Remember that these numbers are only to give you a rough idea of what to expect, and that your results may vary. 

Ford Fiesta ST

Stock (91oct)

Stage 1 (91oct)

Stage 2 (91oct)

Stage 3 (91oct)

Turbo Upgrade

Dyno Horsepower






Est. Engine HP






% Gain Over Stock





27% to 45%+

Dyno Torque






Est. Engine Torque






% Gain Over Stock






Total Price






-Article by Nick Walker

8 thoughts on “Ford Fiesta ST Tuning And Modification Guide”

  1. I run 98 octane in my FiST (US specs) here in Germany. I notice a lot of the US dyno results are based on 91ish octane ratings. How much of a difference would 98 octane make on these tunes?


    1. at least 30 hp or maybe more depending on if you have a tune or not already were talking 7 points up the scale here I know that with a turbo install running 91 octane netted 260 hp and with 93 octane netted 286 hp I run shell 93 octane along with Lucas octane booster racing formula and I can really feel the set of the pants difference in it My fiesta st runs better than all my friends fiesta st does. it is just faster from the factor than all the other fiesta st I have raced and the camshaft are dialed in perfect from the factory and that makes a big difference in the way it runs and all. I call it a factory ringer I had a Yamaha 350 two stroke motorcycle growing up samething it was faster by a good bit more so than my friends motorcycle was the exact same bike just mine was quicker. My cousin had a 1965 Ford galaxie with a 390 four speed my other cousin had the same car but with a 352 engine and it was faster than the 390 of my other cousins car.. This 2018 fiesta ST is by far the best handling car I have ever driven that was stock from factory and it is faster than a focus st also in the canons not straight line performance but in cannons driving I can make better time in my Fiesta than the Focus st or the focus RS it corners flat and it carries more speed into and out of the conners as well.


      1. Thanks, Wayne. I appreciate your thoughts on this. I also love my FiST! Lucas octane booster racing formula? I doubt I can get that over here but I’ll have to look around. I am in the states next week for work and it’s too bad the flammable Lucas stuff would be a huge no-go in my luggage!!!!
        A buddy also has a modified 2018 Fiesta ST and he being the mechanically inclined one of us is helping me build my beast up a bit. I have TB Performane bracing under the car as well as the trunk brace and we just put on the COBB intercooler, intake and a MBRP exhaust. I am not crazy about the loud exhaust and may look at other options down the road, but other than that I am loving the Stage II feel. I love the burble when I let off the gas. The Cobb downpipe should arrive this week and once on the car we’ll go to Stage III.
        I’ve ordered Dynamat and some Second Skin to help with the noise. I did have the backseat out, but that was crazy loud once all the foam in the bottom half of the seat was no longer there to soak up the vibrations and noise.
        If I could find someone over here to put in an LSD I’d consider the turbo upgrade, but so far no one wants to talk to me about that. And, a camshaft is way out of realm of knowledge. Again, thanks for the comments, they were very useful. Chris Baker


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