AEM Cold Air Intake | 2015-2017 Subaru WRX STi (21-735)

AEM Induction Systems
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AEM Cold Air Intake System

The AEM 21-735WB/WR 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 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 tapered 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.


  • Increased horsepower
  • Tuned and dyno-tested to improve acceleration and engine sound
  • Low restriction aluminum tubing
  • Easy to install using commonly available tools
  • Air filter lasts up to 100,000 miles before cleaning is required (depending on driving conditions)
  • Washable and reusable oil-free filter media
  • AEM Lifetime Limited Warranty


  • 2015-2017 Subaru WRX STi


  • Air Filter Color: Red
  • Air Filter Height: 9 in (229 mm)
  • Air Filter Material: Non-woven Synthetic
  • Air Filter Outlet Shape: Round
  • CARB EO Number: D-670-18
  • Clamp Material: Stainless Steel
  • Clamp Style: Regular
  • Clamps Included: 3
  • Intake Pipe Color / Finish: Wrinkle Black / Wrinkle Red
  • Intake Pipe Material: Aluminum
  • 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: 21-2029D
  • Street Legal In All US States: Only on 2015 models (as of September 2, 2016)
  • TUV Approved (Europe): No
  • Weight: 8.9 lb (4 kg)


Customer Reviews

Based on 4 reviews
jesus ponce

Easy installation, sounds good, performs well!

Great product!

This AEM cold Air intake is Amzing you definitely can feel the difference as well as you can hear the turbo building boost and it's awesome great quality product. While installing I noticed one of the strips of rubber pieces for the heat shield was about 2 and half inches to long. I watched a few videos of people cutting that extra rubber of; but I choose to keep it on mine due to once that rubber heats up its possible it can shrink and if it does I'll have extra that way I can adjust it and if not i can cut the extra off later. But definitely hands down I truly recommend this intake.

Great product, fitment question

The product is amazing. It’s a great upgrade from the current stock air box. You can hear that “ spoosh” sound that people look for. Only problem I had was during the installation, I had to cut off some metal piece that was blocking the filter. Other than that, I highly recommend this product !

Mitchell Schaefer
Good product, not direct fit for 2018

I love the product as a whole, I can really hear the turbo now. Also looks like it belongs on the car with the wrinkle red finish. However, the filter was obstructed by something in the way so I had to modify it to work. I also was only able to get half of the bolts to line up. All in all, I'm guessing this isn't compatible for 2018 STI as advertised.