Mountune MR500 Upgrade Turns Mk3 Ford Focus RS into 500hp Beast

The Ford Focus RS Mk3 may be out of production, but Mountune isn’t done making it faster.

Their new MR500 package boosts the hot hatch to 500hp, delivering supercar-level performance while keeping its all-wheel-drive grip and everyday usability.

Ford’s third-generation Focus RS was already a performance icon when it debuted, offering 350hp, all-wheel drive, and the much-loved Drift Mode. While Ford has since shelved plans for another RS, aftermarket specialists have pushed the platform further. Mountune’s FPM375 kit took it to 375hp, the M400X pushed it to 400hp, and now, the MR500 raises the bar once again.

There is one caveat: the MR500 is available only to owners with the M400X package, as it forms the foundation for such extreme output. That package adds forged pistons, stronger conrods, a high-flow induction system, an upgraded intercooler, and a freer-flowing exhaust.

Building on that setup, the MR500 introduces a Mountune-calibrated BorgWarner EFR-7163 turbocharger, upgraded cams and valves, a reinforced downpipe, colder spark plugs, a high-capacity fuel pump, and all the necessary hardware. The kit also features a Turbosmart EFR B1 single-port actuator and a Ni-resist cast turbo adapter for optimal performance.

Carrying over from previous Mountune builds are features like no-lift shift and full-time launch control, ensuring the MR500 delivers relentless pace without compromising usability. With 516 lb-ft of torque alongside its 500hp output, this Focus RS promises serious performance.

Priced at £11,495 including VAT, the MR500 must be installed by Mountune. Starting from a stock Focus RS will require additional upgrades such as forged Mahle pistons (£949), forged conrods (£1,450), an upgraded intercooler (£795), and the £699 mTune handset, making it a significant investment.

Even so, with well-kept Mk3 Focus RS examples still commanding around £20,000, the appeal of creating a 500hp AWD rocket is hard to resist. Mountune’s track record with fast Fords speaks for itself, and the MR500 looks set to continue that legacy.