The 57S-4000 increases horsepower and acceleration by reducing air flow restriction caused by the original factory design. Typical gains on a 4 cylinder vehicle range between 4 and 7 horsepower. This very simple installation replaces the factory air filter and lid with K&N's high-flow, washable and reusable performance air filter and lid. The K&N performance lid is injection molded for extra strength, consistency and durability. It is designed to be easily removed for access to the round tapered washable and reusable K&N performance air filter. The air filter can be used for up to 100,000 miles before servicing is needed depending on driving conditions.This installation can be performed very quickly with only a screwdriver. This 57S performance airbox uses factory holes and the OE air box base, making this a quick and easy bolt-on upgrade. In addition, the 57S-4000 system comes with the air filter end cap. The end cap can cover the top opening. This opening contains an inverted air filter for more surface area and more air flow. For countries which have TUV regulations the end cap must be used. Combine the high flow performance air filter, performance lid and easy installation together and you will have a power adding, TUV compliant, high-flow intake system that will last for the life of your vehicle.
Fitting instructions: http://www.knfilters.co.uk/instructions/57S-4000_inst.pdf
Focus RS mk2305ps 2009 onwards Tuning and Performance Air Filters Specialists GGR Graham Goode Racing Lutterworth Road Aylestone Leicester LE2 8PH England UK Tel 0116 2440080