2008-2014 WRX & STI Cold Air Intake: Best Kits by Engine

For a 2008-2014 WRX, our pick is the AEM 21-478WR. It uses a dry synthetic filter, AEM rates it at 36 hp at 5,300 rpm, and it carries a CARB EO number, so it's legal in all 50 states. For the STI's EJ257, we'd run the Mishimoto MMAI-STI-08 in black or red. Mishimoto claims 25 hp and 25 lb-ft, says it works with the stock tune, and it bolts in under an hour. If you want the biggest flow claim, aFe says its Takeda Stage-2 Pro outflows the factory intake by 63%. If you just want a better filter in the stock box, drop in a Turbo XS or GrimmSpeed panel.

We carry every kit below in our cold air intakes section. Here's how to pick the right one for your car.

Which engine do you have?

Both the 2008-2014 WRX and STI run a 2.5-liter turbo flat-four, but they are not the same motor. Most kits here fit both, but the power, boost hardware and tuning picture differ.

Car	Engine	Factory output	Turbo	Key specs
2008 WRX	EJ255	224 hp / 226 lb-ft	Smaller factory turbo	8.4:1 compression, AVCS on intake cam only
2009-2014 WRX	EJ255	265 hp at 6,000 rpm / 244 lb-ft at 4,000 rpm	IHI VF52	8.4:1 compression, D25 heads (about 51cc chambers)
2008-2014 WRX STI	EJ257	305 hp	IHI VF48	2,457 cc, 99.5 mm bore x 79.0 mm stroke, 8.2:1, dual AVCS

How to tell: if the title or registration says WRX STI, you have the EJ257. If it just says WRX, it's the EJ255. The 2008 WRX is the odd one out. It makes 224 hp on a smaller turbo. Subaru gave the 2009 car a bigger turbo, more boost and a low-density cat, which is how it jumped to 265 hp.

A few product titles list a narrower year range than the maker does. Before you order, check the fitment list on the product page against your exact year. If your WRX is a pre-2008 car, none of these parts are listed for it. Our WRX STI history, every generation ranked breaks down which generation you have.

Best cold air intakes for the 2008-2014 Subaru WRX (EJ255)

The factory WRX intake is built for quiet and cheap. A flat panel filter sits in a plastic airbox fed by a fresh-air duct, and the mass air flow (MAF) sensor reads everything going to the turbo. Every kit below replaces that box with a bigger filter and a smooth aluminum tube. Every one keeps the factory MAF sensor in the loop.

On the 2009-2014 car, the VF52 turbo is the hungriest thing in the bay, so this is where an intake makes the most sense.

AEM 21-478C, gunmetal gray

The AEM 08-14 WRX/STi Cold Air Intake System in Gunmetal Gray (21-478C) uses an oversized, washable DRYFLOW synthetic filter. It has no oil to mess with, and AEM says you can go up to 100,000 miles between services in normal highway driving. A custom heat shield keeps engine-bay heat off the filter, and the factory fresh-air duct bolts to that shield, so you still pull outside air. AEM says it typically goes in under 90 minutes.

One catch: this gunmetal version is not CARB legal and not for sale in California.

AEM 21-478WR, wrinkle red

The AEM 21-478WR Wrinkle Red Cold Air Intake is the one we'd buy. It uses the same DRYFLOW filter, sitting in the old airbox space behind a heat shield, on a mandrel-bent aluminum tube with a textured red powder coat. AEM rates it at 36 hp at 5,300 rpm. The whole kit weighs 7.4 lb.

The red one also carries CARB EO D-670-21, and AEM calls it legal in all 50 states. When you need a new filter, it's AEM part 21-2029DK.

K&N Typhoon, black (69-8004TTK)

K&N built the black K&N Black Typhoon Short Ram Intake (69-8004TTK) for the WRX. It's a short ram: the filter lives where the airbox used to be, behind a heat shield, rather than out in a fender. K&N claims 14.28 hp at 5,228 rpm and 14.3 lb-ft. Those numbers are modest, but the kit carries CARB EO D-269-41, so it's 50-state legal.

The filter is K&N's oiled cotton gauze, replacement RP-5113. K&N says it only needs cleaning every 100,000 miles in normal highway driving.

Injen SP1204WR, wrinkle red

Injen lists the Injen SP1204WR Wrinkle Red Cold Air Intake for both the 2008-2013 WRX and STI. Injen claims up to 33 hp and 32 lb-ft (its summary says 33.2 hp and 31.2 lb-ft). The tube is 6061-T6 aluminum, with a custom heat shield and a dry SuperNano-Web filter (replacement X-1013-BB).

The big selling point is that Injen says it needs no additional tuning and keeps a safe air/fuel ratio. That makes it a good fit for a stock-ECU daily. If you searched for the Injen wrinkle red intake for your 2008-2014 WRX, this is it. Just note Injen's fitment stops at 2013.

Turbo XS WS08-CAI (2008 only)

The Turbo XS 2008 WRX / 2008 STi Cold Air Intake (WS08-CAI) is a 2008-specific part. Don't buy it for a 2009+ car. It's not CARB legal and not for sale in California.

If you have the 224-hp 2008 WRX and plan the common VF52 turbo swap later, keep in mind the VF52 bolts on but needs a custom ECU tune. Build the intake into that tune.

Our pick for the WRX

AEM 21-478WR. It has the biggest maker claim in this group, a dry filter you never oil, a heat shield over the old airbox space, and 50-state legality. If you're outside California and like the darker look, the gunmetal 21-478C is the same idea. If you want a maker that flat-out says no tune is needed, go Injen.

Best cold air intakes for the 2008-2014 Subaru WRX STI (EJ257)

The STI's EJ257 is the stronger motor. It has the IHI VF48 turbo, dual AVCS on both cams and 8.2:1 compression, good for 305 hp in US trim. The factory intake follows the same airbox-and-panel-filter layout as the WRX. These kits swap that out for an open filter, a heat shield and a smoother tube to the turbo. Every kit in this section is listed for the 2008-2014 WRX too.

Mishimoto Performance Cold Air Intake, black and red

The Mishimoto Performance Cold Air Intake in Wrinkle Black (MMAI-STI-08WBK) and the Wrinkle Red version (MMAI-STI-08WRD) are the same kit in two colors. Mishimoto claims 25 hp and 25 lb-ft at 5,300 rpm over the stock intake. The tube is mandrel-bent aluminum with Mishimoto's air straightener and a CNC-machined MAF housing, and the heat shield is powder coated.

Mishimoto says it works with the factory tune, keeps safe air/fuel ratios and installs in under an hour. That's the combination we want on a mostly-stock STI that also sees autocross.

PERRIN PSP-INT-322, four colors

PERRIN's intake covers the widest range of years: the 2008-2014 WRX and the 2008-2015 STI. If you have a 2015 STI that still runs the EJ257, this is your kit, and our VA STI EJ257 mod order guide shows where it fits in the build.

It comes in four finishes:

• PERRIN Cold-Air Intake in Black (PSP-INT-322BK) for the sleeper bay.
• PERRIN Cold-Air Intake in Red (PSP-INT-322RD), the one most people searching "Perrin cold air intake red 2008-2014 WRX" want.
• Perrin Cold Air Intake in Hyper Pink (PSP-INT-322HP).
• Perrin Cold Air Intake in Neon Yellow (PSP-INT-322NY), which looks great against WR Blue.

The replacement element is a 2.75-inch ID, 11-inch-long filter, covered in the maintenance section below.

K&N Typhoon, red (69-8005TWR)

K&N lists the K&N Red Typhoon Short Ram Intake (69-8005TWR) for the WRX STI. K&N claims 17.52 hp at 5,260 rpm and 17.5 lb-ft, a bit more than the black WRX kit. It uses the same RP-5113 oiled cotton filter, mandrel-bent aluminum tube and red powder coat.

California owners should skip this one. K&N's own listing gives an EO number but also says it's not legal for sale or use in California, so don't count on it there.

Here's how the Typhoon kits go together. The high-flow filter (1 in Figure 1) is capped with a carbon fiber top (2). It sits behind the heat shield (3), which drops into the old airbox space. The MAF sensor mount (4) keeps your factory sensor in place, and the mandrel-bent intake tube (5) runs to the turbo inlet.

aFe Takeda Stage-2 Pro (TA-4301P), polished

The aFe Takeda Stage-2 Pro DRY S intake (TA-4301P) has the boldest flow claim here. aFe says it outflows the factory intake by 63% and makes 34 hp and 31 lb-ft. The filter is a large 360-degree Pro DRY S element that needs no oil and cleans with soap and water. This version uses polished tubing, and it ships with all the couplers and hardware.

Pick this one if you want a shiny bay and the most flow on paper.

Our pick for the STI

Mishimoto, in whichever color matches your bay. Mishimoto says it runs on the stock tune, it installs in under an hour, and the CNC MAF housing and air straightener show the kit was designed around the sensor. If you have a 2015 STI, get the PERRIN. If you're chasing the biggest number, the aFe.

Every 2008-2014 WRX and STI intake, side by side

AEM vs Injen vs K&N vs aFe vs Mishimoto vs PERRIN on the WRX

Here's how the brands stack up on this car, using each maker's own numbers.

Brand / kit	Filter	Claimed gain	CA legal	Who it's for
AEM 21-478WR	Dry synthetic (DRYFLOW)	36 hp at 5,300 rpm	Yes, EO D-670-21	Best all-rounder, any state
AEM 21-478C	Dry synthetic (DRYFLOW)	Not stated	No	Gunmetal look, outside CA
aFe TA-4301P	Dry Pro DRY S, 360-degree	34 hp / 31 lb-ft, 63% more flow	No EO listed	Max flow, polished bay
Injen SP1204WR	Dry SuperNano-Web	Up to 33 hp / 32 lb-ft	No EO listed	Stock ECU, 2008-2013 cars
Mishimoto MMAI-STI-08	Not stated	25 hp / 25 lb-ft at 5,300 rpm	No EO listed	Stock-tune STI or WRX
K&N 69-8005TWR	Oiled cotton gauze	17.52 hp / 17.5 lb-ft	Conflicting, treat as no	STI, K&N fans
K&N 69-8004TTK	Oiled cotton gauze	14.28 hp / 14.3 lb-ft	Yes, EO D-269-41	Legal WRX short ram
PERRIN PSP-INT-322	2.75in ID x 11in element	Not stated	No EO listed	2015 STI, color matching

The short version: AEM for the best mix of claim and legality, aFe for flow, Injen and Mishimoto for a stock-ECU car, K&N if you want an oiled filter and a shielded short ram, and PERRIN for year coverage and colors.

Gain claims come from each maker's own testing. Use them to rank the kits, not to predict your exact dyno sheet.

Looking for a Cobb SF or ETS intake for your WRX?

A lot of people land here searching "cobb sf intake wrx" or "ets intake wrx." Many of those searches are really for the 2015-2021 WRX or the newer VB, which are different cars with different parts. If that's you, our best cold air intakes for the 2015-2021 WRX covers that car.

For a 2008-2014 WRX or STI, the kits above are what we stock and what we'd run.

Will a cold air intake void the warranty on a 2008-2014 WRX?

On a car this old, factory coverage is almost certainly long gone, so warranty isn't the real worry. Emissions legality is.

If you live in California or another state that follows CARB rules, buy a kit with an EO number. That means the AEM 21-478WR or the black K&N Typhoon. The AEM 21-478C and Turbo XS WS08-CAI are listed as not for sale in California. Everywhere else, buy on merit.

Does a WRX or STI cold air intake need a tune?

Injen says its kit needs no additional tuning. Mishimoto says its kit works with the factory tune. AEM, K&N and aFe don't say either way.

Our advice: on a stock car, pick the Injen or Mishimoto if you never plan to touch the ECU. If you're already tuned, or headed that way (like the VF52 swap on a 2008 WRX, which needs a custom tune), install the intake first and have your tuner build the map around it. Don't swap intakes on a custom-tuned car and skip the revision.

What does a WRX intake sound like?

An intake isn't an exhaust, so don't expect it to change the boxer rumble. What you get is more induction and turbo noise when you get into boost. Cruising, it's close to stock.

The shielded short rams (AEM, K&N) sit in the old airbox space. The aFe's 360-degree filter is about as open as it gets on this car.

How long does install take?

This is a driveway job with basic hand tools. Mishimoto says under one hour. AEM says typically under 90 minutes.

The general order is the same for every kit: pull the factory airbox and tube, move the MAF sensor to the new housing, bolt in the heat shield, then the tube and couplers, then the filter. Take your time on the MAF sensor and keep your fingers off the element.

WRX air filter: drop-in filter vs full intake

If you want the stock box, stock sound and zero tuning questions, a drop-in panel filter is the move. It won't match a full intake's claims, but it's a five-minute job. Several of these panels fit well past 2014, which helps if you're searching for a 2017 or 2020 WRX air filter.

The Turbo XS Dry Element Drop In Air Filter (AF-01) replaces OEM 16546AA090 and 16546AA10A. Turbo XS lists it for the 2008-2021 WRX and STI. It has an EPDM rubber base rated from -30C to 150C, a coated steel mesh and deep pleats for more filter area. It's dry, so there's no oil to manage. This is our pick for a drop-in.

GrimmSpeed lists the Injen 08-13 Subaru WRX/STi 2.5L (t) Polished Cold Air Intake - SP1204P for the 2008-21 WRX and 2008-18 STI. It's another dry panel, a good choice if you're a GrimmSpeed household.

The K&N 33-2304 Drop In Air Filter is K&N's oiled cotton panel for the 2008-11 WRX and STI, and it also fits the 2005-08 Legacy GT. It's washable and reusable for life.

aFe lists the aFe Magnum FLOW Pro 5R panel (30-10161) for a wide spread of 2008-19 Subarus, including the WRX and STI. It's a solid swap if you also own a Forester or Outback.

Owners of earlier, pre-2008 WRXs often ask about a K&N conical filter for those cars. None of these parts are listed for them, so stick to the 2008+ fitments above.

Cleaning and maintenance

Dry filters are the easy life. AEM's DRYFLOW washes with no oil, and AEM says you can go up to 100,000 miles between services in normal highway driving. aFe's Pro DRY S cleans with soap and water. Injen's SuperNano-Web is fully serviceable, with replacement X-1013-BB. AEM's replacement element is 21-2029DK.

Oiled filters like the K&N Typhoon's RP-5113 need a proper clean-and-re-oil when they're dirty. Go light on the oil, let it soak in, and never put a dripping filter back on the car. K&N says the Typhoon filter only needs cleaning every 100,000 miles on the highway. Dirt roads and winter salt shorten that.

Running a PERRIN intake? The PERRIN replacement filter (X-PSP-INT-324-2) is the 2.75-inch ID, 11-inch element for PSP-INT-322/323/325/326 systems. Keep one on the shelf so a dirty filter never parks the car.

What we'd do

If it were our WRX daily, we'd bolt in the AEM 21-478WR, keep the dry filter clean and call it done until the tune. If it were a stock 2013 STI, we'd run the Mishimoto in black and leave the ECU alone. A 2015 STI gets the PERRIN. A lease-it-forever stocker gets the Turbo XS AF-01 panel.

Once the bay is sorted, wheels are next. Our WRX and STI wheel fitment by era covers bolt patterns and offsets. If you're building on a shoestring, read how we built an STI on a budget. Got a twin in the garage? See our BRZ intake picks. We use the same pick-by-engine approach in our Kia Stinger cold air intake guide.

FAQ

What's the best cold air intake for a 2008-2014 Subaru WRX?

The AEM 21-478WR. AEM rates it at 36 hp at 5,300 rpm, the highest claim among the kits we carry. It uses a dry synthetic filter, sits behind a heat shield in the old airbox space and carries CARB EO D-670-21. If you're outside California and prefer gunmetal, the 21-478C is the same design. For a maker-stated no-tune option, the Injen SP1204WR is the runner-up.

What's the best cold air intake for a 2008-2014 STI?

The Mishimoto MMAI-STI-08 in black or red. Mishimoto claims 25 hp and 25 lb-ft at 5,300 rpm, says it works with the factory tune and quotes under an hour to install. If you have a 2015 STI, the PERRIN PSP-INT-322 is listed through 2015. If you want the biggest flow claim, aFe's TA-4301P says 63% more flow than stock.

Do AEM cold air intake systems fit both the WRX and STI?

Yes. Both AEM kits we carry, the 21-478C and 21-478WR, are listed for the WRX and STI. The difference is legality and finish. The wrinkle red carries a CARB EO number and AEM calls it 50-state legal. The gunmetal is not for sale in California. Check the year range on the product page for your car.

How much horsepower does a cold air intake add to a WRX?

Maker claims on this car run from about 14 hp to 36 hp. K&N claims 14.28 hp (black) and 17.52 hp (red). Mishimoto claims 25 hp, Injen up to 33 hp, aFe 34 hp and AEM 36 hp. Each maker tests on its own setup, so use these to rank the kits rather than to predict your exact result.

Do I need a tune after installing an intake on my WRX?

Injen and Mishimoto both say their kits run on the stock tune. AEM, K&N and aFe don't say either way. If your car already has a custom tune, have your tuner revise it for the new intake. If you're doing the VF52 swap on a 2008 WRX, that swap needs a custom ECU tune anyway, so build the intake into it.

What air filter does the 2008-2014 WRX use?

The factory panel is OEM 16546AA090 or 16546AA10A. The Turbo XS AF-01 is a direct dry replacement for those part numbers. The GrimmSpeed GRM060091 and aFe 30-10161 are also drop-in panels for this car, and the K&N 33-2304 covers the 2008-11 cars. All of them drop into the factory airbox with no tools beyond the box clips.

Will a 2008-2014 WRX air filter fit a 2017 or 2020 WRX?

Some will. Turbo XS lists the AF-01 for the 2008-2021 WRX and STI. GrimmSpeed lists the Dry-Con panel for the 2008-21 WRX and 2008-18 STI. aFe lists the 30-10161 for 08-19 Subarus, including the WRX and STI. The K&N 33-2304 is listed for 2008-11 only, so don't buy that one for a newer car.

Is the K&N Typhoon a real cold air intake?

It's a short ram. The filter sits in the old airbox space behind a heat shield instead of down in a fender. K&N built the black 69-8004TTK for the WRX and the red 69-8005TWR for the STI. Both use the oiled RP-5113 filter with a carbon fiber top and a mandrel-bent aluminum tube. The black one carries a CARB EO number; the red one's California status is contradictory on K&N's own listing.

Which WRX and STI intakes are legal in California?

Buy one with a CARB EO number: the AEM 21-478WR (D-670-21) or the K&N 69-8004TTK (D-269-41). The AEM 21-478C and the Turbo XS WS08-CAI are not for sale in California. Skip the red K&N STI kit there too, since K&N's own listing says it isn't legal in California.

How long does it take to install a WRX cold air intake?

Plan an hour or two in the driveway. Mishimoto says under one hour and AEM says typically under 90 minutes. You'll pull the factory airbox and tube, move the MAF sensor to the new housing, bolt in the heat shield, then fit the tube, couplers and filter. Basic hand tools cover it.

Shop every 2008-2014 WRX and STI cold air intake

Every kit and filter above is in our cold air intakes shop. Pick your engine, pick your color, and send it.

Try wheels on your Subaru WRX STI: see the Subaru WRX STI bolt pattern, wheel sizes by year and wheel builds in our free wheel visualizer.