Fiesta ST Mountune Upgrade Review: +35Bhp M235 Gains

The Ford Fiesta ST stands out as one of the most engaging hot hatches available, celebrated for its sharp handling, lively engine, and accessible price point. Mountune’s performance upgrade takes this supermini to new heights, delivering noticeable improvements in power delivery and responsiveness for a modest investment. This review examines how the kit enhances the driving experience while preserving the car’s core strengths.

Understanding the Mountune Performance Kit

Mountune, a respected tuning specialist closely associated with Ford, offers a straightforward upgrade for the Fiesta ST. The kit primarily consists of a redesigned airbox, high-flow air filter, and recalibrated engine control unit (ECU). These modifications optimize airflow and engine mapping, resulting in significant gains without major mechanical overhauls.

Power output increases from the standard 197bhp and 214lb ft to approximately 232bhp and 258lb ft, depending on the specific kit variant like the m235. Acceleration benefits are most evident in mid-range pulls, such as 31-62mph in fourth gear, which drops by around seven-tenths of a second to 5.7 seconds. This makes overtaking on winding roads far more confident.

• Key components: Secondary inlet duct airbox, high-flow filter, ECU remap.
• Cost: Around £599-£890, installable at Ford dealers.
• Warranty: Does not void manufacturer coverage.

Unlike more aggressive tunes, this package avoids hardware changes to the turbo or intercooler, ensuring reliability for everyday use. Dyno figures confirm peaks during overboost phases, providing usable surge without excessive lag.

Engine and Power Delivery Enhancements

The Fiesta ST’s 1.5-litre three-cylinder EcoBoost engine is punchy from the factory, but the Mountune kit refines its character. Torque builds more progressively between 2,500rpm and 4,000rpm, allowing drivers to stay in higher gears during spirited drives. Where the stock model might demand a downshift for quick progress, the upgraded version surges forward effortlessly.

Official 0-62mph times improve to about 5.9 seconds, but real-world usability shines in roll-on acceleration. The exhaust note gains a throatier edge, adding to the auditory thrill without drone on motorways. Fuel economy remains comparable to stock, as the extra power encourages smoother throttle inputs rather than constant flooring.

These gains make the car feel brawnier across its rev range, ideal for B-road blasts or track days, yet civilized for commuting.

Handling and Chassis Dynamics

The Fiesta ST’s chassis is legendary for its poise, and Mountune wisely leaves it untouched. Torque vectoring control, precise electro-hydraulic steering, and grippy 17-inch tires deliver telepathic responses. Quick direction changes feel effortless, with minimal body roll and planted cornering.

Braking performance is strong, with progressive feel that inspires confidence. The Recaro seats provide excellent support, keeping occupants secure during aggressive maneuvers. On wet or leaf-strewn roads, the system maintains traction admirably, avoiding torque steer even with added power.

While some optional Mountune suspension lowers the ride height for track use, the standard setup suffices for UK roads. It balances firmness with compliance, transmitting pothole impacts as thuds rather than crashes.

Daily Drivability and Comfort

Beyond track prowess, the upgraded ST excels as a practical daily driver. The cabin offers a supportive driving position, with chunky steering wheel and intuitive controls. Infotainment, though dated, functions adequately, and boot space accommodates weekend loads.

Ride quality is firm but not punishing; motorway cruises are stable, aided by the mid-range torque for easy lane changes. Rear seats fit adults for short trips, and visibility remains good. The six-speed manual gearbox shifts with mechanical precision—notchy yet rewarding.

Optional Mountune styling touches, like gear knobs, are subjective; many prefer stock aesthetics for subtlety.

Comparing Mountune to Stock and Rivals

Versus the standard ST, the upgrade adds meaningful pace without altering usability. It’s not transformative like pricier rivals such as the Hyundai i30 N or VW Polo GTI, but at a fraction of their cost, it punches above its weight.

• Pros over stock: Quicker mid-range, better flexibility, enhanced sound.
• Cons: Firmer ride may unsettle passengers; no major top-end gains.
• Rivals: Outshines base hot hatches in fun factor; competes with tuned examples from Renault or Peugeot.

Ownership Costs and Reliability

Running costs stay low: insurance groups hover around 30-35, and efficiency hits 40-45mpg combined. Servicing follows Ford schedules, with the kit’s non-invasive nature preserving warranty claims. Resale values hold strong for modified STs from reputable tuners like Mountune.

Long-term durability appears solid, with no reports of increased wear on clutches or drivetrains in early adopters.

Who Should Consider This Upgrade?

Ideal for existing ST owners seeking more without trading up. New buyers might opt for a base model plus kit over higher trims. Enthusiasts valuing driver engagement over outright speed will appreciate it most.

Frequently Asked Questions (FAQs)

Does the Mountune kit void my Ford warranty?

No, it’s approved for dealer installation, maintaining full coverage.

How much power does the m235 kit add?

Approximately 35bhp and 44lb ft, focusing on mid-range usability.

Is the ride harsher with Mountune upgrades?

The core kit doesn’t alter suspension; optional parts may firm it further.

Can I fit the kit myself?

Professional installation recommended for ECU calibration and warranty.

What’s the top speed after upgrade?

Ford limits it electronically around 144mph; kit doesn’t change this.

Final Thoughts on Value

For under £1,000, Mountune elevates the Fiesta ST from excellent to exceptional. It amplifies strengths—agility, power, fun—without introducing flaws, making it a smart choice for hot hatch fans. Whether blasting country lanes or nipping through traffic, this tuned supermini delivers smiles per mile.