If you’ve ever built a car around the rules for a specific class in a game like Forza Motorsport or Gran Turismo, the right “secret formula” of performance parts can transform a car that’s competitive in a particular class into a timesheet-topping beast. That sometimes means going with an unorthodox combination and setup, but it ends up working beautifully when you know exactly what you’re building the car to do. That’s exactly the case with this particular Ford Focus ST, built specifically to dominate the SCCA STX class, and with a national champion behind the wheel, this is one formidable Focus with a bit of help from Mod Expert Sean.
Jon, who owns this Focus ST, is no stranger to autocross, first campaigning a FWD car in STS with a ’91 Civic Si, then an STR Honda S2000, moving on to win the 2012 National Championship, and last campaigned a STU C5 Chevrolet Corvette. Jon bought the car figuring he needed a more usable daily driver, and the ST is a great car for that, offering daily driver practicality in a package that’ll still perform great being flogged in the canyons. With his experience, he had the feeling that the ST could be an extremely potent Street Touring Extreme (STX) class Autocross racecar. Jon happens to work at OS Giken – those familiar with the JDM tuning scene or limited slip differentials might be familiar with the name, meaning that this car would be receiving an OS Giken Limited Slip diff, among other goodies. With a bit of support from a few other industry friends, the build of Jon’s Focus ST was on.
Cobb Tuning‘s SoCal division hooked Jon up with a suite of go-fast parts for the Focus ST – a Cobb Cat-Back Exhaust and Catted Downpipe featuring a 200cpsi sports cat, Cobb Intake for Focus ST, Cobb RMM for Focus ST, a Cobb knob, and of course, a Cobb AccessPORT to tune the ECU for all of it for the racetrack. Notably absent is a larger intercooler – this is something you’d do on every other Focus ST build, but to fit within the STX class rules, the stock FMIC would have to suffice. The AccessPORT disables the torque truncation limiting power on the stock ecu file, in addition to recalibrating the car for the Cobb Catted Downpipe and other performance parts to make the most of them.
The stock Focus ST wheels had to go as well if Jon was to accommodate the ridiculously beefy tires he had in mind, so a set of Avant Garde M310 Matte Black Wheels in 18×9 ET48 fits within the fenders without the need for fender rolling, and ARP Extended Studs were also fitted. Mod Expert Sean helped Jon out figuring out the offsets and tire widths that would work for what he was trying to do, and the end result speaks for itself.
Featuring full 3in diameter tubing in 304 stainless steel, the Cobb Cat-Back Exhaust for Focus ST performs as good as it sounds, offering a minor bump in horsepower and torque as well as a fantastic growl under throttle.
The Cobb catback has a central resonator to help cut down on drone to make this system easy to live with.
With dual 4in slash cut polished tips, the Cobb exhaust also offers a sportier look than the weird factory hexagonal tip.
Here’s a better look at how the Cobb tips fill out the rear fascia of 2015-16 ST’s.
Of course, working at a race drivetrain manufacturer, one of the first mods Jon put in was the OS Giken Super Lock LSD. Here’s what the Focus ST’s transmission looks like all dismantled so that the new limited slip unit can be installed.
Check out this side by side comparison of the stock diff and the OS Giken Limited Slip. Having driven a Focus ST equipped with a limited slip, I can tell you firsthand that the car feels worlds different with the differential installed and makes much more effective use of the power it makes, putting everything to the ground.
Avant Garde M310 Matte Black 18×9 ET48 265/35-18 at Stock Height
With the wheels on and the Cobb Tuning goodies fitted, it was now time to look at the Focus ST suspension.
A set of Megan Racing External Reservoir Coilovers for Focus ST were what was in store to lower the Focus ST, however the springs the Megan coilovers come with aren’t up for the task of autocross duty.
Here’s the Swift Springs installed.
One of the Focus ST’s other problem areas is the rear sway bar and endlinks. An upgraded rear sway bar and end links help a lot with the ST’s rear end composure.
Check out how the car looks today.
Slung low on massively wide 265-series tires, this Focus ST has enough rubber on the road to wipe the lines off the pavement.
Of course, the enhanced cornering prowess rendered even the factory Recaro seats of the Focus ST less-than-useful, so a set of BRIDE Racing seats have been fitted to keep Jon in his seat as he carves the corners.
From the interior to the exterior, this purpose-driven Focus ST is ready to rock.
Jon hopes to be a strong contender in the 2016 SCCA Nationals, and we wish him the best of luck.
Stay tuned for more features on the amazing vehicles that came out for the meet earlier this month. Interested in modding your Focus ST, or even Fiesta ST? Check out our guides, and then talk to the Mod Experts like Sean – call 714-582-3330 (x8009 for Sean) or just stop by the ModAuto showroom any time during business hours.
Thanks for joining us and we hope you enjoyed the photos!
Story & Photos + Photo Editing Nick Gregson
Select Photos Courtesy Jon @ OS Giken