The Ford Focus ST has three problems: torque steer, exhaust note, and power. Now, the Focus ST is a heck of a vehicle, but it’s missing a little extra something. That’s where Mountune comes in. Wait, who? You might be wondering who Mountune is, but if you’re a Focus performance aficionado, you’re already familiar with their work.

The short version is that Mountune makes the magic happen for the big names racing four-cylinder Fords. The company started in the 1980s prepping Cosworth engines for motorsports and in later years branched out to offer a line of parts that don’t void the Ford factory warranty. The Ford-approved modifications are also smog-legal in all 50 states. This really matters if you reside in one of the more tuning-averse states.

Mountune’s work on the 2015 Ford Focus ST yielded a full complement of modifications that fall roughly into two categories: performance enhancements and appearance enhancements. The performance mods are really the problem solvers of the bunch; the appearance mods solve a different set of problems in a more subjective field. The whole shebang goes for $5,102, though it must be installed by the dealer (Ford or Lincoln), Mountune USA, or an ASE-certified tech to comply with your new vehicle warranty.


Under the Hood
The torque steer and power problems are both solved under the hood, where $1,900 gets you the Mountune MP275 engine kit. That increases power by 18 hp and 26 lb-ft of torque to 270 hp and 296 lb-ft. On the horse-per-dollar scale, the Mountune kit is pretty modest, but we’re told that the upgraded intercooler included with the kit is integral not only to making that power but also to keep it, because heat soak becomes a problem when increasing boost with just the stock intercooler. It’s been a few months since I’ve ripped around in a stock ST, but the tuner gave me a good shove back in my seat when I stomped on it. Far healthier than MT’s long-term Volkswagen Golf GTI.


Adding power alone would just exacerbate the generous torque steer that comes, free of charge, with all Focus ST models. That’s where the Quaife torque-biasing differential comes in: $1,174 (with installation kit) gets you the single most noticeable item in the performance kit. Torque steer is tamed; now the steering wheel just gets heavier when you stomp the gas. Not bad compared to the unintended evasive maneuvers the stock car would make when launched hard with a loose grip on the wheel.

Raw acceleration with the differential and the engine upgrades is noticeable. A stock 2015 Focus ST we tested hit 60 mph in 6.3 seconds, but our modded ST dropped that time to 6 seconds flat. Lining both cars up at the dragstrip would leave the stock ST a few car lengths behind, with the tuner ST ripping off a 14.6-second pass at 96.4 mph to the stock car’s 14.8 seconds at 94.3 mph.

Handling
The stock 2015 Focus ST is no slouch in the handling department, and this is where the problem solving edges into the aesthetic category. If you like the look of a lowered car, the lowering springs are a nice addition, and at $300 they’re pretty reasonable, too. The ride is a little more brittle, but the ST didn’t have much to work with in the first place. Together with the front strut tower brace, the lowering springs bring the lateral acceleration up a smidge, from 0.92 g (avg) to 0.95 g (avg). Although the suspension mods add a bit, the Quaife differential is the biggest contributor to the improved figure-eight time, from the stock 26.0 seconds at 0.73 g (avg) to 25.2 seconds at 0.75 g (avg). That’s almost a whole second faster. Testing director Kim Reynolds attributed the bulk of the improvement to the differential, which allowed him to get on the power sooner than in the stock car.

On streets and winding back roads, the tuner ST distinguished itself nicely. Even with the wheel turned, the Quaife kept the torque reined in, and with the aftermarket intake, the turbo was a bit more vocal. Roll down the windows, roll on the throttle, and enjoy a turbocharged four-piece band. It’s fun. Boost is limited in the first three gears, but mat the throttle in fourth or above, and you get all the turbo can give.


Style
The rest of the performance package falls solidly into the category of “want” rather than “need” for performance. One of my first thoughts after getting into the stock Focus ST (after “torque steeeer!”) was, “This thing is too quiet.” I’m not one for slapping a pair of cherry bombs/glass packs/straight pipes on my daily driver, but something with sporting pretensions needs more than a subtle growl. The Volkswagen GTI, for example, is much too quiet. The stock Focus ST is closer, but the $995 for the cat-back exhaust is money well spent in my book. It’s quiet when you’re just cruising but gets loud when you get on the gas hard.


The short shifter ($449) is said to make shifts more precise. It moves the knob much lower, though, making you grip it a little bit awkwardly. I’d pass on it because the stock shifter is far from vague, but if you’re changing the shift knob, it might be worth it for you. I’d rather put my money toward a set of wheels. That short shifter is like a wheel and a half from most of fifteen52’s catalog. Just sayin’.


The Complete Package
MT’s short list of must-have items:
  • Mountune MP275 engine kit
  • Quaife torque biasing differential
  • Cat-back exhaust system


For a factory backed, warranty-keeping performance package, the Focus ST doesn’t go too far, but I think it goes far enough. If you’re a year into your payments and the thought of voiding your warranty has you a little leery, then the Mountune-sourced performance package is worth a look.

2015 Ford Focus ST (Ford Performance)
  • BASE PRICE $25,195
  • PRICE AS TESTED $30,297
  • VEHICLE LAYOUT Front-engine, FWD, 5-pass, 4-door hatchback
  • ENGINE 2.0L/270-hp/296-lb-ft turbo DOHC 16-valve I-4
  • TRANSMISSION 6-speed manual
  • CURB WEIGHT (F/R DIST) 3,247 lb (61/39%)
  • WHEELBASE 104.3 in
  • LENGTH x WIDTH x HEIGHT 171.7 x 71.8 x 58.4 in
  • 0-60 MPH 6.0 sec
  • QUARTER MILE 14.6 sec @ 96.4 mph
  • BRAKING, 60-0 MPH 111 ft
  • LATERAL ACCELERATION 0.95 g (avg)
  • MT FIGURE EIGHT 25.2 sec @ 0.75 g (avg)
  • EPA CITY/HWY/COMB FUEL ECON 23/32/26 mpg
  • ENERGY CONS., CITY/HWY 147/105 kW-hrs/100 miles
  • CO2 EMISSIONS, COMB 0.74 lb/mile