Subaru Impreza Air Filters and Induction Kits

Subaru Impreza WRX & STI Air filters and Induction kits

Cosworth-induction-kit Subaru Impreza WRX & STI Air filters and Induction kits

One of the first upgrades owners carry out on their Subaru Impreza, Forester, Legacy & BRZ is to upgrade the Air Filter to a performance one, for better flow and therefore better performance or simply to replace a dirty filter.

The purpose of an Air Filter is, as the name suggests to filter the air entering the engine to avoid damage to the engine and keep the required clean air flow into the engine, without an Air Filter your engine’s life would be drastically shortened.

Air flow into the engine is measured by the Subaru ECU using a Mass Air Flow Sensor or MAF Sensor which sits after the Airbox and is used by the ECU to ensure the correct amount of fuel is used.

Performance Panel Air Filters are a direct replacement for the original part and fit into the standard Subaru factory Airbox.   Fitting is simply a matter of unclipping the top part of the Subaru Airbox an sliding out the old panel air filter then replacing with the new one and with prices starting at just over £30 they are always a popular choice, check here for 2001-2007 Air Filters or here for the later models

Cosworth_Performance_Panel_Filter_Impreza_TurboWRXSTi_9207_714_7424 Subaru Impreza WRX & STI Air filters and Induction kits

For the Subaru Impreza turbo models including UK 2000, WRX and STI there are 2 sizes of air filter.   The first is a rectangular filter and suits the Classic Impreza Turbo models from 1993-2000 and the New Age Bugeye, Blobeye and Hawkeye WRX and STI models from 2001-2007.  This filter is approximately 280mm x 168mm on the outer edge that sits on the ridge of the bottom part of airbox. 

The 2008-2012 Hatchback WRX and STI, 2011-2013 Saloon STI and 2014-2019 STI models use a nearly square filter approximately 222mm x 216mm. 

459124 Subaru Impreza WRX & STI Air filters and Induction kits

We stock a variety of Panel Air Filters for the Subaru Impreza, Forester and Legacy models, from market leaders and well known tuning brands such as K&N Filters, Cosworth, Green, Blitz, HKS and of course the genuine Subaru range also. Take a look at our shop for information and prices

All filters use either a dry polyester gauze (such as Cosworth), or a slightly oiled cotton gauze (as used by K&N Filters) or a foam filter such as used by HKS.

Many of the filters will need replacing at standard service intervals, however K&N’s filters are warranted for lifetime when used with their cleaning and re-oiling kit, so although slightly more expensive to purchase initially they can work our cheaper in the long run.

Panel Air Filters can usually be fitted to the Subaru models without any changes to the ECU map and therefore make a great first purchase for those looking to replace a worn filter or just add a better flowing model.

Several years back one of the Japanese Tuning magazines wrote a feature on testing several Panel Air Filters with Dyno Results, it’s worth tracking down this article if you’re interested in measured differences between Subaru Air Filters.

The other option is to remove the original Subaru factory fitted airbox and replace with a cone induction kit, either as a standalone filter in the engine, or with either a cold air feed to the cone filter or a shroud or surround to prevent hot air from the engine entering the filter, as of course the colder the air the better the performance.

k_n-69-8001twr-2 Subaru Impreza WRX & STI Air filters and Induction kits

As Induction Kits are a substantial change from the factory airbox, they are usually fitted in conjunction with an exhaust and sometimes fuel pump upgrade, and therefore an ECU remap also.  We would generally recommend always having the ECU map checked and / or changed following fitment of an induction kit.

Induction kits also usually make a substantial change to the induction sound from your Subaru, meaning you can hear a sucking or induction road upon acceleration

We stock a wide range of Induction kits for the Subaru Impreza Classic Turbo, WRX and STI models including Blitz’s SUS cone filters, HKS’s mushroom filters, Cosworth’s Blue kits and of course K&N’s wide range of induction kits, check this link for more details

Several of these manufacturers produce both stand alone induction kits and Cold Air Feed or enclosed induction kits, such as K&N’s excellent Apollo Cold Air Feed systems and their Short Ram kits.  K&N guarantee a improvement in power with many of their induction kits, usually when fitted in conjunction with an ECU remap.

Induction kits are more expensive than panel filters with prices starting at around £185 but generally offer better performance along with a better sound and look great in the engine bay.

Servicing of the Induction kits is simply a matter of assessing the condition of the cone filter come service time and cleaning or replacing as necessary.

Performance Panel Air Filters and Induction Kits are generally legal to use in most countries however we strongly advise you to check this before fitting as some countries and USA States do now allow for modifications such as these.  As these are an upgrade to your Subaru over and above what was fitted at the factory we always recommend advising your Insurance Company and also checking with your dealer if your car has warranty, to ensure fitting does not void this.

Specification Overviews for some of the popular Air Filters and Induction Kits is shown below

K&N 0646 Induction kit

Guaranteed to increase horsepower

Designed to improve throttle response and engine sound

Replaces entire factory air intake system

Not legal for highway use in states adopting California emission regulations

Washable and reusable lifetime air filter

Lasts up to 100,000 miles before service is required (depending on driving conditions)

Easy to install, usually in 90 minutes or less

K&N Million Mile Limited Warranty

K&N 33-2232 Panel Air Filter

Designed to increase horsepower

Washable, reusable, and engineered to last for the life of your vehicle

Designed to provide high airflow and exceptional filtration

Engineered to fit easily into your factory air box

10-Year/Million Mile Limited Warranty

Only needs cleaning every 50,000 miles under normal highway driving conditions

Emissions legal in all 50 States

Will not void vehicle warranty

Cosworth Panel Air Filter 20002270

Improved performance & Superior filtration.

Exceptional dust holding capacity.

Reduced restriction (10%+ compared to OE filters).

Over 98% efficiency (ISO5011:200 Fine Dust Test).

We hold good stocks of all the main Air Filters for your Subaru Impreza, Forester or Legacy including Cosworth, K&N, Green, Blitz and

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