That cuts the hot hatch's 0-62 mph time by more than half a second.

Owners of the latest Fiesta ST can now buy a new aftermarket upgrade that dramatically improves performance.

Created by well-known Ford tuning firm Mountune, the m225 package increases the hot hatch’s power output from 197 bhp to 222 bhp, as well as changing the car’s torque delivery. Whereas before the 1.5-litre turbocharged engine delivered 214 lb-ft of torque at 1,600 rpm, the m225 pack takes that up to 251 lb-ft and offers it lower down the rev range, making the engine more responsive.

As a result, Mountune says the m225 pack slashes the Fiesta’s 0-62 mph time by more than half a second, bringing it below the six-second mark. And similarly, the company says the extra torque has cut the in-gear 31-62 mph acceleration by a full second.

Ford Fiesta ST Mountune m225

The upgrade, which includes a high-flow induction kit, essentially achieves these performance gains by allowing more air to enter the cylinders, then modifying the engine tuning. Although the induction kit is a mechanical upgrade, the ‘re-map’ for the engine is installed using Mountune’s SMARTflash system. Combining a smartphone app and a Bluetooth receiver that plugs into the car’s OBD II diagnostics port, the system allows the driver to flip between varying set-ups with their mobile phone.

Three calibrations are included with the upgrade, giving customers the option of stock settings or Mountune’s high-performance set-up, as well as an anti-theft immobiliser setting designed to keep the desirable hot hatchback safe from the criminal fraternity.

“SMARTflash makes it incredibly easy for our customers to switch between vehicle calibrations in as little as two minutes, just using their phone,” explained David Moore, director of Mountune. “It adds a new level of convenience and functionality to our packages and embodies our forward-thinking approach to vehicle performance upgrades. The new Fiesta ST is the perfect platform to launch this DIY-friendly, pioneering technology. No laptop, no wires, no handsets – no problem!”

Ford Fiesta ST Mountune m225

And despite the significant increase in torque, power and performance, Mountune says the upgrade does not “compromise” the Fiesta ST’s safety or reliability, claiming the car has undergone “extensive” testing to ensure the upgrades don’t damage any components.

“With that almost instantaneous delivery of torque the ST really comes alive, but you also have peace of mind in knowing that this is an engineered upgrade,” said Moore. “As with all Mountune packages, the m225 has undergone extensive performance and durability testing with all safety parameters retained. This is not just the best upgrade for the Fiesta ST, it is also the most robust.”

Gallery: Ford Fiesta ST Mountune m225 upgrade