Why the AEM 21-779C Makes Your FA20DIT Happy
✔ Legit Power Gains
AEM typically shows +10–15 horsepower and better torque delivery across mid-range RPM.
Translation: less lag, more punch, more smiles.
✔ Enhanced Turbo & BOV Sound
Prepare to hear your turbo spool and your bypass valve flutter like it finally discovered caffeine.
The AEM 21-779C 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 Mazda 6 models.
✔ Crisp Throttle Response
No more mushy on/off feeling. The motor wakes up, and your right foot becomes slightly more dangerous.
✔ AEM DryFlow Filter
No oil. No MAF-sensor drama. No “I swear I didn’t over-oil it” moments.
✔ Heat-Resistant Intake Tube + Airbox Shielding
Cooler air in, hotter power out. Because heat soak is basically the WRX’s love language.
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.
Installation: WRX Owner-Friendly
Subaru folks love wrenching, so this 45–60 minute install is basically foreplay.
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No cutting
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No tuning required
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Basic hand tools
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Instant gratification
After installation, you’ll immediately do a “quick test drive” that somehow becomes 45 minutes. Don’t worry — we’ve all been there.
The air intake tube is constructed from mandrel-bent aluminum featuring a durable gunmetal gray powder coated finish. This air intake system was developed to accommodate the engine’s factory emissions control devices including the mass airflow sensor and breather tube. 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).
Final Verdict
The AEM 21-779C Cold Air Intake System is one of the best bang-for-buck upgrades you can throw at the FA20DIT Subaru WRX. You get real performance gains, cleaner flow, spicy turbo noises, and a better driving experience — all without breaking anything (probably).
It’s the perfect choice if you want your WRX to feel sharper, faster, and more alive every single time you smash the throttle.
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 21-779C vehicle applications to determine the legal status for each vehicle.
Nurseman –
Exactly as described, cold air intake kit for 2.5L Mazda3/6. Fit like a glove in my 2014 Mazda3, and the instructions were very clear and simple. Kit was complete, and I was able to do this with a screwdriver and a couple nut drivers. Worthy upgrade, easy to do, and adds a great low growl when you get on the gas.
Jason Diaz –
So far I’m very pleased with my cold air intake. I bought it for a better price on here so I was already happy about that. It was a pretty simple installation when I put it in. The instructions said it would take 90 minutes to do but I changed mine out in about 40 minutes. I’ve definitely seen a change in my gas mileage and my rpm’s I’ll post a video on here soon with how the installation looks, but also before and after driving videos. If you are worried about hydro locking with this, it shouldn’t be a problem. The position of the the intake is pretty high and also hard for water to get to it. I’ve taken my car through plenty of car washes (car in neutral) and haven’t had any issues. If you have any questions though feel free to ask! I know I didn’t cover every aspect of this product yet.
Prime viewer –
So this device is supposed to offer 3 options – more robust sound, more power, better fuel economy. My take:Sound is perfect – the right amount without sounding like some wannbee fast and furious mod. Love the sound. Power – maybe? I think the testing they did added 6HP to a 2.5 liter Mazda 6 (Mazda uses engines across car lines and the CX-5 I have has an the same 2.5 Litre motor). Do I feel more zip? Maybe but likely it is psychological. Not likely you will “feel” a 6 HP gain in most vehicles. Economy? I haven’t noticed any fuel economy gains but I haven’t seen a drop off either. (I’ll caveat I have a throttle modifier installed as well – a push button device that sets the “drive by wire mode”. If you have seen cars that have a “Sport” and “Normal” switch, this works similar except it has 6-7 modes.) In any case, sound is perfect, power is good (even if only psychological) and I don’t see a positive or negative in regards to fuel economy. One thing – the directions did not include a step for one part of “stripping” – not sure If I can describe it here but if you have a left over piece of stripping, go back and use it to line the hole in the “box” the intake tube goes thru. Overall, pleased with product, instructions are generally good. If you can get it for $200 – I would consider it close to perfect.
jpl91988 –
It dose exactly what you want it to do. It may not provide much power without a proper tune. But it dose sound and look great. Also it was an easy direct fit. My gas mileage has definitely dropped due to my heavier right foot. lol
Bishop –
The AEM 21-779C Performance Cold Air Intake is a great addition for my 2018 Mazda 6, in terms of sound, performance and mileage, when driving with an economy mindset. From start to finish I never would have thought the installation experience would have went as smooth as it did. And once you’re complete with the task, you’ll definitely enjoy the outcome.Before beginning installation I cleaned my engine with P21S Total Auto Wash. After compressed air drying my engine, I began installation of the AEM 21-779C Performance Cold Air Intake Kit, by removing the negative battery terminal first, then I just followed the included instructions that come complete with photos. After completing installation it was now time for testing… And I must say, you will definitely notice the power gain, throaty sound, and increase in power, but because I’m an economy enthusiast, my greatest experience was the increase in mileage of about 2.5 MPG.Final thoughts: The AEM 21-779C Performance Cold Air Intake is a great addition for anyone interested in adding a cold air intake system to their vehicle.
Abubakr Sharif –
So to start off. This thing is pretty good. But mine really wasn’t so great. The tube for the intake itself was bent. Which really sucks because otherwise the thing was perfect. One more thing is that the sleeve for the MAF sensor actually doesn’t even fit. Check the photo. I had to cut it off to make it fit, this leaves the chance of debris so make sure if you do this to CLEAN thoroughly. The part that was bent was a bummer and the quality suffered from it. Hopefully you don’t have to encounter that issue. Otherwise the setup is great.I give this 3 stars since Amazon was so kind to help me out with my quality issue. Again don’t let this shy you away, it’s great. Just something that happens you know.As far as the actually sound. It’s awesome! Above 3-4K RPMs is where it really comes alive. And is discreet below that. Goes well with a nice axle back exhaust setup but can totally be run on it’s own
Richard Blankenship –
Good price, easy assembly, and great sound!!
Elena5280 –
I was a little hesitant to buy one at first but I went threw got one and I’m glad I did..it shipped fast came one time boxed up and stuffed safely came with pretty easy to understand instructions with pictures..easy to install took around 30 minutes and I’ve never really worked on cars other then a few small things but it was worth it I absolutely LOVE the sound the car makes now just a deeper growl you can definitely hear and feel the slight change I’m happy with it and would recommend..
Armando Garza –
Resonancia
Esperaba mejor resonancia
Alexander –
Easy to instal and great added sound
Perfect fit for my 2018 CX5 took 5 minutes to instal and a great fit.