The kit boosts the standard car’s 2.5-litre turbocharged engine from 222bhp to 256bhp, while pulling power is up from 236lb/ft to 295lb/ft.

Acceleration from 0-60mph is reduced by 0.6 seconds to just 5.9 seconds, making it one of the fastest accelerating front-wheel-drive cars on sale.

View more pictures of the Ford Focus ST Mountune

And it will hit 100mph from a standstill in an impressive 14.1 seconds, quicker than the previous generation Ford Focus RS and similar performance to a 276bhp Nissan 350Z.

The kit has been designed and tested in partnership with Ford by Mountune and costs £1,120 plus fitting.

It consists of a larger intercooler and high-flow air filter – to make the motor more efficient – and recalibration of the engine management system.

Ford claims the parts have been extensively tested both on British roads and at the Nurburgring circuit in Germany for their performance and durability.

View more pictures of the standard Ford Focus ST

A sports suspension kit is currently under development and will be available by next year.

Fitting the kit does not affect the vehicle warranty and the performance parts come with their own warranty.

And, the tuning parts can be fitted to used cars as well as new Focus ST’s – a tempting proposition as early 2006 models can now sell for around £10k.

For less than £15k it’s possible to get your hands on a Ford Focus ST which will be almost as quick as the forthcoming Focus RS in a straight line.

We’ve driven the Ford Fiesta ST Mountune 185 and found it one of the most fun superminis on sale, with excellent handling and performance.

Have you modified your car? Have your say on the Auto Trader Blog