FORD’S Fiesta and Focus ST models are already some of the quickest mainstream motors – and now they can be faster still, thanks to officially approved upgrades from tuning specialists Mountune.

In the case of the Focus ST, the mods increase power to 275PS and produce acceleration from rest to 62 mph in less than six seconds. The cost starts at just £1225 and the upgrade takes 90 minutes at a Mountune-approved Ford dealer.

The Mountune tweaks give the Fiesta ST a power output of 215PS, enough to get it from rest to 62 mph in 6.7 seconds – the cost in this case is just £599.

Both upgrades are compatible with the cars’ standard Ford warranty, so Mountune modified vehicles are still fully covered against mechanical failure for three years or 60,000 miles from the original date of purchase.

We tried the STs on Llandow racetrack. Click here to see what we thought.

Click here for our car review of the Fiesta ST….

…and here for our review of the Focus ST.