Why Upgrade Your Forester with the AEM 21-874C?
Because your engine wants more air, and the stock setup is choking it.
The 21-874C brings you:
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Improved airflow through mandrel-bent aluminum tubing.
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Faster throttle response and better mid-range feel.
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A more audible induction sound (yes, you’ll hear the engine breathe).
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A washable, reusable Dryflow filter (oil-free) with up to 100,000 miles service interval in optimal conditions.
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Gun-metal powder-coated intake tube for durability and appearance.
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Heat shield to reduce intake temperatures and avoid engine-bay heat soak.
For a Forester that wants more response and less “just cruising,” “21-874C” is a smart mod.
This Performance Air Intake System allows your engine to breath more air compared to the restrictive factory air intake housing. It is designed, tuned, and dyno-tested to produce more horsepower and torque.
Key Features of the AEM 21-874C Cold Air Intake
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Mandrel-bent aluminum intake tube, gun-metal finish. aemintakes.com+1
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AEM Dryflow air filter (oil-free, reusable) capable of long service intervals (up to 100k miles).
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Custom heat shield with edge-trim lining, designed to isolate intake from engine-bay heat.
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Dyno-tested gains: e.g., estimated +8.05 HP @ 4,358 RPM on this configuration.
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Complete hardware kit including clamps, couplers, mounting brackets.
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Backed by AEM’s limited-lifetime warranty.
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Note: Not currently legal for sale or use in California on pollution-controlled motor vehicles for this part.
The cone-shaped AEM Dry flow 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). A custom shaped heat shield with edge trim lining is included to keep engine bay heat from the air intake.
Performance Expectations
With the 21-874C installed, you can expect:
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Better throttle tip-in: your Forester feels sharper when you step on the gas.
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Improved mid-range power: for passing, merging, or giving the car a little gauntlet throw.
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More visible and audible induction: you’ll hear more of what the engine’s doing.
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Intake temperatures moderately reduced under load thanks to improved routing.
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Slight horsepower/torque gain (manufacturer estimates ~8 HP) — real-world gains vary.
aemintakes.com
It won’t turn your Forester into a WRX, but it will make it feel more alive and responsive.
The air intake tube is constructed from mandrel-bent aluminum featuring a durable gunmetal gray powder coated finish.
Daily-Driver Friendly?
Absolutely — for what it is.
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Works with stock ECU; no immediate tune required.
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Dryflow filter means less frequent maintenance and no oil mess.
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Retains factory mounting points and clean installation.
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Keeps everyday reliability intact; you still get the practicality of your Forester, just with more character.
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BUT: Since this part is not CARB legal for sale/use in CA (for this application) you should check local legality if you’re in California or states with similar restrictions.
This air intake system is backed by AEM’s Lifetime Limited . 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 vehicle applications to determine the legal status for each vehicle.
Installation Overview
Time: ~45-90 minutes depending on tools and experience.
Steps:
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Remove the factory intake box and associated ducting/resonators.
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Install the AEM heat shield in place of the stock cover.
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Fit the gun-metal aluminum intake tube, secure with clamps and couplers.
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Mount the Dryflow filter in its position, transfer any sensors (MAF) from old intake.
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Verify clearances (especially near moving items or heat sources).
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Tighten all hardware, inspect for secure fitment, start engine and listen for the new induction tone.
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Monitor for check-engine lights or sensor issues (unlikely if installed correctly).
From the manufacturer
Jon –
Super easy install, perfect fit on my 2019 Forester Sport. Filter is up in the engine bay enough that water shouldn’t be an issue but I still put a filter wrap on mine. Could not believe the coolant jug sized silencer hooked to OEM airbox. Loud when you send it, quiet during daily drive. Noticable difference in throttle response. Not sure I gained the 8 hp claimed by AEM, but it sure feels and sounds more fun. Also came with a license plate frame which adds 10 hp when installed properly.UPDATE: had it on and running for a while now. No issues at all, put stock box back on for a little bit and found myself feeling a dip in power ( I know, I was shocked) I put it back on and everything is right again. I know it’s not making it a race car, but I’m trying to pull any power out of this that I can, no matter how small.
Amazon Customer –
Just installed it on My 2022 Subaru Forester Wilderness! Fits great. Everything works. Also installed a Addw1 oil catch can. This is a perfect combo! The sound in SI drive is sublime . Worth the money!
Ken M. –
Handled with care. Fits perfect for Subaru forester 2020.
Julian Montero –
Sounds so good! Great fitting and easy installation. Best aftermarket part in my Forester so far.
Brett K –
Was excited to get this and start installing it but the stock Subaru mass air flow sensor does not match the AEM holes as seen in images. So had to return it.
Dennis –
Didn’t fit. Wasn’t returnable. Wouldn’t purchase the product again. Did allot of research and was quite disappointed.
rob garofalo –
This is absolutely perfect! The quality is right on target and love the product!
CuRiOuSfIsH –
I got this for the wife’s MY20 Fozzy Sport. She’s not a car enthusiast but has picked up some knowledge from my car hobby. She was actually excited to get it. AEM has been around for a very long time, and this intake is built to their high standards. Everything fit perfectly, included instructions were not the most detailed but the install was easy with the tools indicated in the instructions. As far was what the intake does, it adds a lot air induction noise and at full throttle, it’s fairly loud. It’s up to you to decide if it’s worth the $.