Although the Focus ST pulls strong straight off of the showroom floor, there’s always room for improvement. After evaluating the factory intake system, Mountune concluded the primary restriction to be the plastic crossover pipe and air filter. Many times automakers will choose to recycle a part between various vehicles due to cost. In this case, the cross-over duct on the Focus ST is shared with several other vehicles in a “one-size-fits-all” manner. However, Mountune used this opportunity to engineer a product that outperforms the factory unit.
To replace the factory plastic unit, Mountune developed its cast-aluminum cross-over duct. This duct features no internal obstructions and a fixed volume of 1.8 liters, a 38-percent increase over the factory unit. When installed with the included high-flow air filter, Mountune claims that this setup translates to an airflow increase of over 50-percent for the same delta pressure drop.
Included in the induction kit are the cross-over duct, high-flow air filter with dual inlets and Mountune/Samco silicone coupling hose with clamps that securely attach the filter to the duct.
Most factory intercoolers can only withstand mild amounts of heat-soak and then the power levels begin to quickly drop. Although the factory Focus ST intercooler works great at factory power levels, Mountune uncovered a few key areas for improvement.
Mountune’s high-flow intercooler begins with a larger and more efficient 14-row tube-and-fin core mated to lightweight alloy end tanks. This direct-replacement intercooler retains the OE mounting locations and integrates ram air guides to direct airflow through the core. Not only does the Mountune intercooler fit like a factory piece, but it also allows the use of OE intercooler hoses. By retaining the same intercooler track as the factory intercooler system, turbocharger response is maintained. Due to the increase in intercooler size, the Mountune unit requires removal of the active grille shutter.
Many tuners swear by bar-and-plate intercoolers as a superior design for all applications. Quite simply, it’s not true. Not only do bar-and-plate intercoolers usually weigh twice as much as a comparably sized tube-and-fin intercooler, they also suffer from a much higher pressure drop over the intercooler core. This effectively means that the turbocharger has to work harder to feed the air back into the engine. According to Mountune, this intercooler offers up to a 44-percent decrease in pressure drop over the stock unit.
mTune Calibration Device
mTune is Mountune’s flash tuning device for loading the optimized MP275 calibration to your Focus ST’s ECU. The mTune comes preloaded with the MP275 tune developed by Mountune specifically for the addition of the induction kit and intercooler. Unlike the Cobb AccessPORT, this unit does not allow custom flashes due to potential warranty issues.
While this unit doesn’t allow for any custom tuning, it does ensure consistency, reliability and drivability of the vehicle’s performance. Additionally, the mTune includes features such as a 0-60 time display, data logging, six OBD channel monitoring and more. Users can even configure the mTune as a shift light.
Each mTune device comes complete with a holster with t-slot mounting, OBD2 and USB connection cables, carbon-fiber effect faceplate and zip-up case.
While not an official part of the MP275 package, Mountune’s high-flow cat-back exhaust complements the induction kit, intercooler and tune to extract even more horsepower from the Focus ST. This 50-state legal exhaust system features 2.5-inch 304 stainless-steel mandrel-bent tubing, laser-cut flanges and TIG welding throughout for optimal strength and aesthetics. Mountune also chose to incorporate slip-fit connections at various points to allow for easy installation and adjustment.
Each muffler in the system integrates three-layer Hybrid Synthetic sound absorption packing that Mountune claims will eliminate droning, booming and other undesirable tones. Due to the use of consistent internal diameter tubing throughout and the proprietary muffler packing, this exhaust system does not exceed the 95db government standard.