So you’ve just bought yourself a Fiesta ST, and you want to make more power. Great! That’s easily doable – but speed costs money. However, if you’re clever, by going in the right order, you’ll get the most possible power for as little money as possible. In the next few paragraphs we’re going to cover what mods will give you the most return on every modding dollar, so you can make serious torque even on a shoestring budget. We’re not going by order of “how to get to stage III“, because that much is obvious – we’re covering what mods you can do to increase the power of your Fiesta ST while spending as little as possible.


First, I’ll give you guys the best bang for the buck mod there is, available for the low, low, LOW price of FREE, this mod can be done by anyone with a Fiesta ST and a sharp razor blade.

This simple intake mod makes a big difference in intake air temperature, and has a huge impact in how quickly the car can shed heat once you get moving.
The OEM intake tube that feeds the airbox (that S-shaped tube that connects to the radiator area at the very front of the airbox) – it draws from an area of the bumper that’s totally sealed off from any fresh incoming air, instead it draws hot air from in front of the radiator – basically sucking in hot air and heatsoaking the car. Airflow works differently for different cars, but this made a big difference in keeping the car cooler in stop and go traffic and in the staging lanes at the track.



Ford_Fiesta_ST_Injen_Intake_Cobb_Downpipe_FMIC_Intake_mod-6 Ford_Fiesta_ST_Injen_Intake_Cobb_Downpipe_FMIC_Intake_mod-8 Ford_Fiesta_ST_Injen_Intake_Cobb_Downpipe_FMIC_Intake_mod-9
Another way of saying this is HOW TO REDUCE INTAKE AIR TEMPERATURES IN A FIESTA ST… so By cutting an opening in the wall closing off the intake from getting any fresh air, the car draws in much cooler air and will make more power – and this mod is effective for anyone running an intake type that retains a lower airbox, so this is a great mod if you have the COBB Fiesta ST Intake already. To get access, just remove the plastic phillips retainer closest to the headlight, and bend the radiator cover plastic upwards. It is extremely flexible, and I assure you, unless you bend the hell out of it, it’s not going to crack or anything. Easy, 5 minute no-harm-no-foul mod that actually makes a difference.

I run this mod myself with a hybridized version of the Injen Intake for Fiesta ST, running Injen’s intake tube into my stock lower airbox with a custom filter and airbox lid like Cobb’s design, but with a modified lower airbox, drawing from the idea Mountune had with their lower airbox. I’ve verified after testing a few other Fiestas that my results were not unique – cutting the hole helps a LOT with intake temperatures.


COBB, Injen and Mountune’s intakes aren’t free, but the simple, free and virtually undetectable mod of just opening up a hole to let fresh air reach the intake inlet will continue to help as you mod out your Fiesta ST more. We have to imagine Ford closed it off for people that live in areas that get a lot of precipitation (rain, snow, etc).

It doesn’t matter how much power your Fiesta ST makes if you drive like crap. I don’t care how good a driver you think you are, even if you’re a multiple-time SCCA regional Champion, you owe it to yourself to make the trip.
If you’ve bought your ST within the last YEAR, did you know that you get a FREE Two Day Racing School clinic at Ford Racing School at Miller Motorsports Park in Utah?
While getting to Utah and where you stay there is up to you, Ford pays 100% of your tuition for the school, feeds you dinner Day 1 and feeds you breakfast, Lunch and Snacks Day 2. Sign up for FREE ST Octane Academy Racing School For ALL NEW FIESTA ST BUYERS HERE. You can take a spouse or friend with you for an extra $495, but they won’t get to drive any of the schools Focus ST’s or Fiesta ST’s so I don’t feel like it’s worth the $495. The racing school teaches you how to do E-brake tricks as well as teaching you how to get around the track using the fastest line possible, and on your instructor hot-lap ridealong, you’ll see how stupid fast the car can be around the track with a pro at the wheel. I’m a reasonably quick driver, and the pros at the Octane Academy took turns a good 10-15mph faster than I do – it’s one of the few times I’ve actually been scared with someone else driving. Anyways, I promise you you’ll come back from Octane Academy with a big stupid grin, Octane Academy Attendee exclusive ST badges and be MUCH FASTER with your car back home. One of the guys in my STOA class happened to be a SCCA regional champion, and he recommends it even if you’re a regular autocrosser. Beyond coming back a faster driver, it’s also a hell of a lot of fun – see for yourself, check out our blog about it here for the Hoonigan Reception and HERE for Race Day at Ford Racing School.


To begin with, I’m going to turn everything you’ve probably heard about modding on its head and say that before you ever worry about the exhaust system or intake – there’s two key items that would be more effective uses of your modding dollar in terms of bang-for-the-buck. A cat-back exhaust system is actually the least power/dollar for the Fiesta ST, and that’s why it’s one of the last things to think about unless SOUND is your main concern.


First, you’ll need a tune. The easiest is the Cobb AccessPORT V3 for Fiesta ST, which is loaded with a number of “off the shelf” performance maps – these are generic tunes and while they’re a huge improvement over stock, a custom tune will yield maximum power – and custom tunes are easiest to get on an AccessPORT, or alternatively a SCT X4 Tuner for Ford – the X4 is cheaper but the screen response is slower, and there aren’t as many custom tuners that support STs using SCT software at this time. Right off the bat, this makes a huge difference in torque, because it disables a function called “Torque Truncation”, which limits your output in gears 1-3, robbing you of nearly 30lb/ft at the wheels, which the AP gives back to you. Alternately, if you’re on a budget and want something super easy and painless, the Turbo Transformer for Fiesta ST gives you an additional 2psi of boost once the car exceeds 13psi for a little bit of extra power when you want it, but leaves operation otherwise stock when you don’t have your foot in it – we liken it to the JB+ Modules for the Mini Cooper that BMS offers.

A new feature COBB has added to the AccessPORT, with v200 and newer off-the-shelf maps, you now have the awesome ability to switch between maps on the fly, so you can instantaneously switch from full performance to economy mode by just pressing Cruise Control “CAN/RES” and then Cruise Control “+” or “-” to switch between maps without stopping – I do it all the time on roadtrips, cruise in economy, but switch back to power for hills or passing to get the car to eke closer to 40mpg highway, despite my daily being a “Stage III” Fiesta ST – and with that they also added Launch Control and “Flat-Foot Shifting”, which enables you to keep your foot to the floor even while shifting, keeping the car in boost between gears.

After the tune, the next biggest concern is the INTERCOOLER. The Fiesta ST’s Front Mount Intercooler is incredibly easy to replace, and the intercooler is the most critical component for making power. YOU CANNOT USE STAGE II MAPS WITHOUT THE FRONT MOUNT INTERCOOLER. I see it all the time on the forums and on facebook groups, kids running stage II and III maps, despite still having the stock front mount intercooler and well, it makes me sad, guys. It’s dangerous and counterproductive to do run Stage II on the stock FMIC – the car will run more aggressive timing than it can safely run and be running on hotter air, which makes less power anyway, so please don’t be that guy – there is no way around it. So to be extra clear, once again – You can’t even go to Stage II without the Intercooler. This applies to the Focus ST as well – and seems to be a common issue for most modern turbo cars, including the Mustang EcoBoost.


Personally, I have the COBB Front Mount Intercooler for Fiesta ST fitted, but don’t run the COBB chargepipes with it, though many people like to run the COBB Chargepipes. The cold side chargepipe is not really a restriction, but the hot side, which has the infamous resonator donut, IS a restriction. ATP Turbo and Forge Motorsport both offer a hotside chargepipe that omits the resonator donut thing for a 1.5kpa (appx) reduction in pressure drop. Mountune also offers the hotside.

The Intercooler itself does not actually ‘make’ horsepower, but rather it allows you to run more aggressive air/fuel/spark, thereby allowing you to make MUCH MORE power than the OEM intercooler can support – and if you live somewhere hot, a front mount intercooler is practically a must whether or not you are planning to tune the car. A car that runs cooler makes more power than a car that’s running hot. That’s all there is to it.

Check it out – here’s some really helpful information from our friends on – an important thing to remember here is that while it is true that the J-line is the biggest and cheapest FMIC available at this time that doesn’t require replacing the crash bar, it’s also the heaviest and the most difficult to install – if you’re doing it yourself that’s fine, but the extra labor will really add up if a shop is installing it for you. If you’re having a professional install it for you, go for direct-bolt-in.  Huge shoutout to Razor on for putting this info together.

Stock FiST IC
Core Dimensions:
27.5″ x 5.25″ x 2″
Core Volume:
288.75 in


The list is in order of Core Volume.

Mishimoto J-Line IC
Core Dimensions:
22″ x 7.2″ x 3.75″
Core Volume:
594 in
69.1589% difference over OEM FiST IC
18.1818% difference over Cobb IC

Cobb IC
Core Dimensions:
27.5″ x 6″ x 3″
Core Volume:
495 in
52.6316% difference over OEM FiST IC
5.6075% difference over ATP IC

Core Dimensions:
24″ x 6.5″ x 3″
Core Volume:
468 in
47.3736% difference over OEM FiST IC
1.2903% difference over AIRTEC IC

Core Dimensions:
28″ x 6″ x 2.75″
Core Volume:
462 in
46.1538% difference over OEM FiST IC
9.4122% difference over Mountune IC

Mountune IC
Core Dimensions:
29.25″ x 5.75″ x 2.5″
Core Volume:
420.47 in
37.145% difference over OEM FiST IC
3.4401% difference over OEM FoST IC

Stock FoST IC
This Can Be Retrofitted, but Requires EXTENSIVE IRREVERSIBLE Modification of Car because outlets are much closer together than Fiesta ST. Unless it’s free, it’s more trouble than it’s worth.

Core Dimensions:
26″ x 6.25″ x 2.5″
Core Volume:
406.25 in
33.8129% difference over OEM FiST IC
4.0816% difference over Levels IC

Levels IC
Core Dimensions:
26″ x 5″ x 3″
Core Volume:
390 in
29.8343% difference over OEM FiST IC
19.6224% difference over Mishimoto Z-Line IC

So in order of Bang-for-the-Buck for Fiesta ST, the order thus far is Tune, then FMIC.

Next after the intercooler in terms of HP-per-dollar is the downpipe.

You have two choices here – and remember, none of the downpipes on the market at this time for the Fiesta ST are CARB legal, unfortunately, though that may be a possibility later. So you have a decision to make. How loud do you want to be, how cheap do you want to be, do you ever have to pass any kinds of emissions tests/inspection, and does the smell of gas bother you?

If you don’t like a smokey tailpipe, the stink of unburnt fuel, the thought of the EPA or CARB slapping you with a massive fine, then you’re going to want a Catted Downpipe. While yes, a catless downpipe is always cheaper because it doesn’t include any of the expensive catalyst material and makes slightly more power than a catted downpipe, it’s louder, tends to cause white smoke to pour from your tailpipe and when you’re idling, your car will smell like gas. Forget impressing a date, and a catless downpipe definitely won’t pass the “wife” test. Anyone who says it doesn’t smell is either lying to you or has something wrong with their sense of smell.


If you don’t like the smell of gas, or are worried about potentially drawing unwanted attention, a catted downpipe’s the way to go, and that’s what I did myself. When I’m going to be running the car competitively on the track, I swap in my COBB Catted Downpipe for Fiesta ST on the car – because I want the power, and also, I had a Volvo that smelled like gas all the time and it drove me nuts, so I really dislike the idea of my NEW car smelling like gas, so catted was my only real choice. Milltek also offers a high flow Catted Downpipe for Fiesta ST as well, which though spendier than the COBB unit, is one hell of a nice piece and shines like a piece of jewelry.

Running a downpipe will cause a Check Engine Light unless you either run a tune that disables the rear O2 sensor or you add an O2 spacer or something – whether it’s catted or catless, you’ve got a check engine light in your future. So be prepared.

Before installing a downpipe, check your local state regulations- and it’s worth mentioning that at this time, we are unaware of any CARB legal downpipe options.

So after the downpipe, then you can move onto your Intake. Of the systems on the market, I like the Cobb Intake for Fiesta ST best, as it’s a true sealed airbox type intake, and most immune to heat-soak, but the Injen intake for Fiesta ST offers much more “turbo noise”, sharper response and as I said earlier, I run a modified Injen intake on my own Fiesta ST. I loved the change in character it gave the car.
If you want that “Blow-off Valve” sound, skip the useless and potentially power robbing “BOV Spacer” and just get a high flow intake, trust me, it’s pretty loud without being “bus airbrakes” loud. As you can imagine, I’m personally not a fan of blow-off valves on a car fitted with a factory recirc system, but it’s a question of personal preference. It’s your car, do what you want, just know it may actually lose power for the sake of noise.

Then at the very end of the tuning-for-power road – at least before getting crazy and messing with the turbo – is the catback exhaust. The catback often doesn’t even make 10whp of difference, and is often the most expensive part of the exhaust system, though MBRP Exhaust for Fiesta ST is a true 3in system and easily the most affordable bolt on exhaust for a Fiesta, and given that some other local members are having trouble with odd boost spikes with “custom” fabricated exhausts by a random “muffler shop”, it’s worth spending a little more to get a bolt on exhaust engineered for the car without anything wonky done to it.

So to recap, the ideal order to maximize your horsepower gains per modding dollar spent on a FIESTA ST is Tune, Intercooler, Downpipe, Intake, Exhaust.

It’s important to remember we’re only talking about POWER MODS here, as there are quite a few very inexpensive mods that make the driving experience better.

Some of the cheaper mods that make the car better are things like the Cobb Rear Motor Mount for Fiesta ST which gets rid of the annoying clunking when shifting in 1st 2nd and 3rd and restricts engine movement, reducing the amount of horsepower lost to unwanted drivetrain movement and generally makes the car feel worlds better. Our project Fiesta ST has been running one for over a year, and we recommend that as a “First Mod” for anyone who’s just gotten the car, and at $155, they’re wicked affordable.

Beyond that, have you noticed that the gas pedal is kinda sunk in deep relative to the brake and clutch pedals, making it nearly impossible to heel-toe? The Active Shift Designs Gas Pedal Lift Spacer for Fiesta ST is just $54.99 and corrects the problem – it’s such a “must” for the car, Automobile Magazine put one in their Long Term Fiesta ST, and TheSmokingTire fitted Chris’ Tuxedo Black Fiesta ST with the spacer as well – it corrects one of most people’s biggest gripes with the car.

Last, while you can’t get my totally awesome Projector Headlights for Fiesta ST here in the USA without importing a set yourself, you can get wayyyy better lighting by replacing the OEM fog light assemblies completely with a set of Diode Dynamics Luxeon LED Fog Lamps for Fiesta ST – at $155 for the pair, they’re a huge upgrade in light output and a nice aesthetic change. Pair these with a Diode Dynamics HID kit for Fiesta ST and you won’t be able to “outdrive your headlights” on your local canyon road anymore. While less than ideal, the reflector pattern of the Fiesta doesn’t glare at all when fitted with HIDs and still throws a reasonable cutoff line.

Thanks for reading and we hope we were able to share some new information with you, even if you’ve been modding your ST for a while.
Be sure to join us at our next monthly Ford ST/EcoBoost meet Saturday April 25th 11a-1pm, we’ll be hosting a ST Performance Clinic and have two big manufacturers of ST Parts out to show off their goodies and talk ST performance. We hope to see you there at 1721 E Lambert Rd Unit C, La Habra CA. ALL FORDS WELCOME. 🙂


Story & Photos Nick Gregson
Ford Fiesta ST Owner/Enthusiast/Expert
Find me on, & as BlueBomber !
Special Thanks to Razor &