Mountune gives the Focus RS over 500bhp

Published: 20 August 2019

► Mk3 Focus RS gets 50% more power
► Mountune tune costs around £6000
► M450 kit offers more subtle upgrade

The hot hatch game is moving at a fast rate – the new ‘warm’ Focus ST now uses the same engine as the old Focus RS as a base, and the frankly silly 415bhp Mercedes-AMG A45 has set the bar even higher. All those numbers make the outgoing Focus RS look pretty ordinary – but Mountune is fighting back with a tuning pack for the ageing hot hatch.

The Brentwood firm has unveiled a new range of upgrades for Ford’s soon-to-be-replaced flagship, with a new M520 pack giving it a metric 520hp, or 513bhp in old-fashioned imperial ponies.

That puts it well ahead of Affalterbach’s latest effort, and miles ahead of the original’s 345bhp. Mountune says it’ll set you back £5974, but if that’s a little too much money or power for your tastes, a more affordable £2950 M450 pack with 450hp or 444bhp is also available. Torque on tap is 516lb ft for the 520 kit, while the 450 option puts out 428lb ft of torque.

How the Mountune Ford Focus RS kits deliver their muscle

Most of the power comes from a new BorgWarner EFR series turbocharger, which uses ceramic ball bearings for lower friction and quicker response rates. The M520 also gets an uprated fuel pump as well as revised camshafts and an upgraded valvetrain, all designed to ram more fuel/air mixture into the 2.3-litre engine and develop more power.

‘With the very latest BorgWarner turbocharger platform, both upgrades deliver exceptional levels of power and torque, turning the RS into something quite remarkable,’ said Alec Pell-Johnson, director of Mountune Performance. ‘After the positive initial feedback we received from the official unveiling of the kits at Ford Fair, we can’t wait to start fitting them to our customers’ cars.’

By Curtis Moldrich

CAR's online editor and racing-sim enthusiast