We know we’ve been posting a lot of Ford Fiesta ST stuff this past week, and we’ll be back to our regularly scheduled programming soon – but when Christmas Came Early for the Project Fiesta ST, we had so much awesome stuff packed into one install, we figured you guys wouldn’t mind just one more Fiesta ST post. So we’ve made quite a few upgrades to our project Fiesta ST since we last wrote about it.

Before we started, our Fiesta ST was basically stock, save for the addition of a Cobb Tuning AccessPort V3 for Fiesta ST, a Cobb High Flow Air Filter and modded stock airbox, paired with a bespoke Pro-Tune by Randy Robles of Mountune USA, whom specializes in CARB and Manufacturer-compliant tuning solutions, which Nick installed independently for off-road evaluation. Our Fiesta ST’s wheels were a set of XXR 512s, a lighter option than the factory wheels and at 17×7 ET38 and hubcentric rings and TPMS sensors, this is one of the few direct bolt-on wheels that are fully compatible with the car. In addition, the Cobb Tuning Rear Motor Mount significantly enhanced the feel of the car by arresting unwanted engine movement, making for a more balanced car.

The rear torsion beam of our Fiesta ST has also been upgraded with a Steeda Rear Torsion Beam Brace, modified to fit an ST, which helps correct the 3-wheeling behavior of the car, much like the Eibach Rear Sway Bar for Fiesta ST.


We had quite the stockpile of parts for our Fiesta ST – we laid them out by order of where they’d go, the COBB Front Mount Intercooler for Fiesta ST in the box by the bumper, the coilovers marked, the Cobb Fiesta ST Downpipe in the skinny box and the catback comprising the rest of the Cobb Turbo Back Exhaust System for Fiesta ST in the largest box. The shop was booked solid at the time, so being a hands-on type of guy, Nick took it upon himself to evaluate and install the system at home, figuring it’s best to see how the system is for the average enthusiast to install.


Before I got on to the business of installing the full Cobb Tuning Fiesta ST Turbo-Back Exhaust system, I laid everything out and checked the contents of my boxes before starting the install. It’s no fun to have your car half-apart only to discover your upgraded part is missing hardware, plus it gave us a good visual idea of how it laid out relative to the car.


The bulge in the Fiesta’s downpipe is because the Cobb Downpipe for Fiesta ST is a Catted Downpipe, meaning your exhaust won’t be stinking of unburnt fuel, it’s street legal in much of the USA, and though not yet CARB approved for street use, and though we’ve yet to put the car on a dyno, the difference in response is ridiculous. While these are simply “butt dyno” anecdotes and not hard data, what we can tell you for sure is that the Cobb Downpipe yields MUCH faster spool up and boost delivery is damn near instantaneous – no more waiting around as boost climbs from 14-15psi up to 18.5-19 – oh no, now the car delivers all 21 psi at the drop of a hat. As far as bang for the buck performance goes, if you already have a Cobb Tuning AccessPort V3 for Fiesta ST, this 49-state legal and possibly CARB-legal someday catted downpipe has to be one of the biggest power gains for the car.

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The COBB Fiesta ST Cat Back Exhaust section is quite well dialed in – when I first installed the system, we were expecting it to be pretty loud – we were surprised when the Cobb Fiesta ST exhaust was hardly any louder than stock at idle, but snarled and popped at higher RPM. As with any exhaust system, it’s subjective, but personally, our opinion of the sound is that it’s very well balanced, offering an exhaust note that’s deeper without being annoying or obnoxious. It’s exactly what you want from an exhaust.


The dual tips of the Cobb Exhaust system also give the car a lovely, bespoke touch and a hint at whose exhaust is under your Fiesta.

Then it was time to fit the COBB Front Mount Intercooler, the other key component in taking your Fiesta ST to Stage III. As we’ve said before, an intercooler itself doesn’t make power, the intercooler allows your engine to work more efficiently and make its power more consistently. The OEM chargepipes have this restrictive “resonator donut” which bottlenecks the flow of charged air in the intake, and the OEM intercooler is overwhelmed by basically anything over stock, so the COBB FMIC upgrade is definitely well worth the effort. Installing the intercooler itself is surprisingly easy and took about half the time it took to install the COBB FMIC in a Focus ST.

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Take a listen to the exhaust note with the turbo back setup fitted and Stage III tune loaded.

With the power of our Fiesta ST cranked up significantly, now we could turn our attention to the Fiesta ST suspension.

Earlier this summer we ordered a set of ST Suspensions XTA Adjustable Coilovers for Fiesta ST, and at long last it was time to install them. Since our Project Fiesta ST is a daily-driven commuter as well, we needed to choose a coilover that could cope with the conditions of LA’s harsh roads.

Update: With over twenty thousand miles on them, the improvement in ride quality is noticeable, and these coilovers have stood up to some incredible stuff, including a long drive down a 2wd Truck Trail that SYNC decided was “a great way to come down Palomar Mountain”. I can’t recommend the ST Coilovers for the Fiesta ST enough.

It’s hard to explain, but the car rides smoother in general, but transmits a lot of shock when crossing potholes and so on, as you might expect of any coilover. As far as coilover conversions go, this is actually a pretty good tradeoff and for the purposes of pleasing this writer’s very sensitive spine, the ST Suspensions XTA Coilovers for Fiesta ST are a great choice – with KW Shock Bodies they’re quality dampers, but the ST may not be the best idea if you live anywhere that salts the roads. Since we live in Southern California where most people don’t even know what snow looks like, we’ve got nothing to worry about.

fiesta-st-cobb-fmic-turboback-st-coilovers-007 Here’s our coilover before installing it.

fiesta-st-cobb-fmic-turboback-st-coilovers-008 We ended up setting the ride at about 17 threads so the car has about two fingers’ worth of clearance, offering both a lowered stance as well as enough room for the suspension to still do its thing without rubbing.


 The ST Suspensions Coilovers went in without too much trouble, the only modification we had to make was simply widening the shaft hole for the rear shock mount by about 1mm so the fatter shaft of the ST rear damper could pass through. All said and done, for the effort and improvement in ride quality over the Fiesta ST’s notoriously HARSH stock ride, the ST Suspensions Coilovers were a great way to go. Take a look at how the front coilovers look after installation. The XTA coilovers feature adjustable rebound damping as well as top-mounted camber adjustments for quick changes at the track.


With the lowered ride, our project Fiesta ST is not just looking better, but handling better with a gentler overall ride as well. The Cobb Tuning Turbo-Back Exhaust and Front Mount Intercooler, we’re able to switch up maps with our AccessPORT from Stage I to Stage III – taking our HP from approximately 187whp to approximately 212whp/280wtq, based on what other Fiestas with the same parts have yielded on the dyno – of course, we’ll let you know what the real figure is once our own Dynojet AWD Dyno comes online in summer 2016.
Check out the gallery below and let us know what you think! fiesta-st-cobb-fmic-turboback-st-coilovers-025 fiesta-st-cobb-fmic-turboback-st-coilovers-024 fiesta-st-cobb-fmic-turboback-st-coilovers-023 fiesta-st-cobb-fmic-turboback-st-coilovers-022 fiesta-st-cobb-fmic-turboback-st-coilovers-021 fiesta-st-cobb-fmic-turboback-st-coilovers-020 fiesta-st-cobb-fmic-turboback-st-coilovers-019 fiesta-st-cobb-fmic-turboback-st-coilovers-017

If you’re interested in upgrading the performance of your Fiesta ST, talk to theFord ST Mod Experts at ModBargains. Call 714-582-3330 (x8004 to speak to Fiesta ST specialist Robert) or chat live at www.modbargains.com for modding advice from our friendly and enthusiastic Modification Experts.

Story & Photos by Nicholas Gregson