Mountune says the change is designed to improve the driving experience, as well as performance.

Ford tuning specialist Mountune is well known for upgrading the Blue Oval’s hot hatches, but the company has evidently decided its existing option for the Fiesta ST just wasn’t potent enough. As a result, the firm has added a new package that squeezes a handful more horses from the little hatchback.

Dubbed the m235 upgrade, the new package is a step above the existing m225 option, which eked 225 bhp from the 1.5-litre turbocharged petrol engine. With the £575 upgrade, however, that is increased to 232 bhp, while peak torque rises to 258 lb-ft.

Despite the increase in power, though, the upgrade is based on the m225 package, which uses the Mountune induction kit. That includes a tig-welded aluminium air box with a secondary cold air feed point, a high-flow air filter and a porous secondary air-feed hose. Not only does that allow the company to increase the car’s power, but it also increases induction noise to add aural appeal.

Both packages supplement that with a phone-controlled tuning system that changes the way the engine behaves. In the case of the m235, that means the power delivery has been modified to “transform” the driving experience. There’s an enhanced exhaust sound, as well as a no-lift shift setting that makes upshifts smoother without the need for the driver to lift off the throttle.

The system comes with three settings, including an anti-theft setting that allows the driver to immobilise the car so it cannot be driven away. By the same token, there’s also a setting that returns the car to its standard state of tune. The third and final setting, however, is the full-bore 232 bhp setting, which includes modifications to the sport and track modes to make the launch control system more aggressive.

Ford Fiesta ST Mountune M235

And although these upgrades incorporate significant changes to the car’s performance and hardware, Mountune says the packs are designed to ensure “the vehicle remains safe and reliable”. The company also says it aims to provide an “OEM-plus” feel to the car, giving the impression the vehicle left the factory with the upgrade attached.

“The m235 power upgrade shows how much fun there is to be had from the Mk8 Fiesta ST,” said Alec Pell-Johnson, director of Mountune Performance. “We’ve worked hard to improve on the already impressive m225 kit and with the introduction of no-lift shift optimisation and an enhanced exhaust overrun, our latest kit provides drivers with a product that delivers both significant performance and driver enjoyment.”

The Mountune m235 kit costs £575, although customers who already have the m225 upgrade can switch to the m235 for £99. Both prices are inclusive of VAT.

Gallery: Ford Fiesta ST Mountune M235