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AEM Cold Air Intake 

The AEM 21-478WR Performance Cold Air Intake System produces horsepower and torque gains by replacing your vehicle’s restrictive factory air filter and air intake housing. This air intake system was designed, tuned and dyno-tested to fit specific Subaru WRX, WRX STI, Impreza WRX and Impreza WRX STI models. Air enters the system through an oversized AEM Dryflow synthetic washable air filter for outstanding air flow, filtration and performance. The air filter is located in the original air box space and is protected by a heat shield which is designed to reduce intake air temperature and increase horsepower. The intake tubing is constructed from mandrel-bent aluminum featuring a durable textured red powder coated finish. This air intake system was developed to accommodate the engine’s factory emissions control devices including the mass air flow sensor. The cylinder shaped AEM Dryflow air filter is made from an oil-free, synthetic filter media that can be used for up to 100,000 miles before cleaning is needed (depending on driving conditions). The air intake system is easy to install with commonly available tools and it is backed by AEM's Lifetime Limited Warranty. Some AEM air intakes are not legal for sale or use in California and other states adopting California emission standards while others are 50 state legal. View the 21-478WR vehicle applications to determine the legal status for each vehicle.
Pricing: $349.99
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Item # 21-478WR

Estimated Horsepower Gain 36 HP @ 5300 RPM

Air Filter Color Red

Air Filter Height 9.125 in (232 mm)

Air Filter Large End Diameter 6 in (152 mm)

Air Filter Material Non-woven Synthetic

Air Filter Outlet Shape Round

Clamp Material Steel

Clamp Style Regular

Clamps Included 3

Intake Pipe Color / Finish Wrinkle Red

Intake Pipe Ports All intake tube ports needed for the specified applications are included

Mass Air Flow Sensor Adapter Included Mass Air Flow Sensor Adapter Included When Required

Product Box Height 12.25 in (311 mm)

Product Box Length 20.25 in (514 mm)

Product Box Width 12.25 in (311 mm)

Product Style AEM Cold Air Intake System

Replacement Filter 21-2029DK

Street Legal In All US States See Application Link Above

TUV Approved (Europe) No

Vacuum Tubing Included No

Weight 7.4 lb (3.3 kg)



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  • 8.0 lbs.
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