Air Filters and Intake Systems

We stock a wide range of high flow air filters and intake systems for your Focus ST MK4

Forge FMINDK37 Replacement Filter


This is a replacement high flow, pleated, synthetic nanofiber filtration air filter (an upgrade compared to the more common, cotton filter) for the Forge Motorsport uprated induction kit FMINDK37  

£54.35£45.29 (ex. VAT)

Direnza Ford Focus MK4 ST 2.3 18+ – Cold Air Induction Kit


All Direnza Cold Air Induction Systems are supplied with a high quality, cone style air filter; designed to replace the OEM airbox, offering more surface area compared to the standard filter. Direnza air filters are manufactured from premium grade, washable cotton, ensuring long-lasting performance enhancements.Direnza Cold Air Induction Kits include lightweight alloy pipework mandrel-bent for accurate placement on your vehicle, and coated with a premium grade, black textured finish for a sleek appearance.Designed in-house by Direnza engineers, our Cold Air Induction Kits reduce blockages and significantly enhance air flow into the engine compared with stock induction arrangements, boosting your car’s soundtrack and performance.Heat-resistant silicone hoses are supplied with every Direnza Cold Air Induction Kit. An often-overlooked item, our easy-fit silicones are layered for extra durability, their 5mm wall consisting of four polyester layers finished with jet black pigment.Designed to replace the OE setup, providing up to 50% more filter surface area to help maximise capacityEngineered to help the 2.3 Ecoboost engine breathe easier and improve throttle response from your Focus STGains in power and torque are noticeable over a larger RPM rangeA straightforward way to give your ST a sporty, performance soundtrackComplete kit includes mandrel-bent alloy pipework, high quality cotton filter and high performance silicone hoses            Filter Bore Size:3.5"

£249.99£208.33 (ex. VAT)

Forge Ford Focus ST MK4 280 Induction Kit


Gains of up to 17BHPBlack powder coating for ultimate protection and durability.  Forge Pleated performance air filter No engine management check lights (EML) Increased air flowLifetime warrantyThis FMINDK37 is the cold air intake system for the Ford Focus ST Mk4 and has been designed to improve airflow in several key ways. It routes the air more directly into the vehicles engine, using an increased diameter CNC mandrel bent alloy pipe. This induction system also improves the airflow by adding our Forge high flow pleated air filter, in place of the more restrictive factory air filter.The choice of air filter was made after many rolling road sessions and data logging test drives. As we have seen many times before with Ford power plants our Forge Hi-Flow pleated air filters gave the best results. The construction and build quality of the filter oozes superior quality and enhances the ST 280s engine bay. Forge Hi-Flow filters are made using a premium quality, high flow, synthetic nanofiber filtration media which is pleated to maximise surface area and in turn increase air flow.The CAD designed, laser cut, and precision folded heat shield is designed to form a barrier between the air filter and radiant heat from the engine. It also helps duct the cold air to the air filter, to help preserve low intake temperatures. The heat shield is designed to incorporate the OEM air duct and fits directly to the standard factory air box mounting points and rubbers without the need for modification.The diameters on this air intake have been carefully tuned to provide exactly the correct quantity of air flow into the turbo charger, ensuring consistent power gains throughout the rev range without any loss of low-end torque, increasing power and enhancing induction acoustics for added character and excitement.We used Performance Remap in Gloucester with their VTEC 4 wheel-drive dynamometer, this was to ensure all our data has been collated independently, The results below speak for themselves, Testing and development took place on a MK4 ST 280 with Mountune STAGE 1 software. The stock dyno pulls gave a base figure of 307 BHP at 5458 RPM, from simply swapping out to the Forge Motorsport Intake in the matter of around 30 minutes, yields of over 17 BHP were achieved.When studying the dyno graph below the peak torque figure does appear to be 5NM below the stock airbox figure however please take note of the 17NM gained from the Forge Motorsport induction kit throughout the midrange.With both the BHP and torque figures held higher throughout the rev range your engine will definitely have the edge and feel more responsive when pushed to its limits. As with all Forge Motorsport products we offer a no quibble lifetime guarantee on all parts of this kit excluding the filter.

£324.44£270.37 (ex. VAT)

Direnza Ford Focus MK4 ST 2.3 2018+ Vortex Cold Air Induction Kit


The VORTEX SERIES Intake for the Ford Focus MK4 ST is a high performance Air Induction Kit. Designed, developed and tested in-house over the past 12 months by Direnza’s team of highly skilled engineers.Every aspect of the kit has been designed from the ground up with quality & performance at its heart. Direnza’s Vortex system combines OEM fit & finish whilst providing significant power gains across the rpm range.Dyno proven gains of +15.2bhpCFD-Optimised wide mouth inlet allows both sides of the slam panel air feeds to be used for increased air flowFully enclosed Airbox to combat high engine bay temperatures3.5” Aluminium Crossover pipePowder coated in a wrinkle blackAir-tight, Proflex grommet absorbs natural engine movementTriple layer reinforced silicone turbo elbowTo maximise the dual intake design, we recommend removing the upper radiator shroud located behind the front bumper and opening up the passenger side slam panel air feed.Click here to download fitting instructions                        

£349.99£291.66 (ex. VAT)