AEM DryFlow Air Filter 28-20304

Ok, Subaru’s have a well designed intake system. They’re already cold air intakes, and have special resonance chambers to prevent maf scaling issues caused by engine resonance noise. If you install an aftermarket intake system, there WILL be air resonance problems around 2500 and 5000rpm. This resonance will effect the maf ability to monitor air flow. It will report less air than what is actually entering. Leaning your af ratios, and lowering power. This is well reported on Multiple performance forums, and there are many examples from ecu logging.

Solution? Use a dryflow if you want better flow.
These dryflow filters have almost a 20% lower restriction compared to the stock paper filters. That is a pretty good improvement, but they will allow more dirt into your engine. Better than oiled filters, but still worse than paper. So if you live in a dusty Environment with dirt roads, I’d actually recommend you stick with stock.

These filters fit amazing. They’re tighter fitting than paper filters, so you may have to undo the intake hose clamp and remove the rear of the airbox.

Bought this for a 2017 WRX, even though Amazon said it would not fit the car (might not be updated for newer model years). AEM & SubiSpeed both had this model number listed for my car, so I took a chance. This car is new to me and I actually had more trouble opening the hood for the first time than I did swapping out the filters. The filter itself is not perfectly square and other reviewers advised of this, if I had not been aware of this in advance I may very well have been one of those guys trying to pound the square peg in the round hole. If I knew how to open the hood properly in advance I may have been able to make the swap in less than a minute.

Packaging? The Amazon box the filter was shipped in was impeccable, as always; however, the box from the manufacturer was pretty beat up. The filter was wrapped in plastic inside the box and I did a thorough inspection before breaking the plastic. This is the only reason for 4-stars and not 5. Sorry, I should have taken pictures, but my first outing after installation was to the recycling center and I didn’t feel like digging the box back out of the bundle since the filter itself was in good shape.

First drive after install I noticed slightly increased throttle response and acceleration. Not mind blowing, but enough to feel a difference. Some reviewers said they noticed a difference in the sound; however, I haven’t had the car long enough to pick up on that. I am hoping for better fuel economy down the road, but since I wanted to play with my new toy today my average mpg actually went down a little bit. If I remember I may come back in about a month, after a few commutes on the interstate, for an update on fuel consumption.

I’ve always preferred AEM filters because they’re no-oil, high build quality, and I’ve used AEM products about as long as I’ve owned cars. First off, i’d like to say “thank you” to all the WRX reviewers whose feedback i leaned on heavily to decide whether or not to take a chance on this filter. It was a risky choice given all the “doesn’t fit” reviews readily found on the web.

Let me say this: IT FITS PERFECTLY. On my 2019 WRX Base 2.0L. Note for future reviewers: it’s really helpful if you mention your model, year, and engine. Sometimes i wasn’t sure if folks had the 2.5L STI, or a WRX like mine. Anyway, i clicked the “Helpful” button for all you folks that had helpful WRX reviews. Thanks again.

As was mentioned by another reviewer, despite all the web reviews that it doesn’t fit — not helped by the fact that neither Amazon nor AEM list it as a compatible part for a 2019 WRX Base — it does. This is the same filter i put into my 2014 XV Crosstrek, with the same airbox setup, and the entire process took under 5 minutes. I’m not a super-proficient modder, i tend to stick to basic bolt-on stuff like bracing and that, but this was really easy. A couple non-pro tips:

– The filter only goes in one way, by design. The pleats align vertically (unlike the OEM paper filter), and there is an embossed “AEM” logo and “DryFlow” brand mark on the TOP edge of the filter. Put it in that way and it just drops into place. Easy.

– You should absolutely remove the intake duct in front of the airbox, It’s so easy that *anyone* can do this, no modding experience necessary. There are two plastic pins securing the duct to the front of the engine bay. Pop them out with any flat screwdriver, the air duct pulls away easily with no force necessary. This will allow you to open the airbox wide enough to replace the filter.

– Drop the new AEM filter in with “AEM” logo on top, pleats running vertical, as i mentioned. You may need to wiggle the airbox a little to open it up enough to fit the AEM filter in, but it will open up plenty wide enough with that air duct out of the way.

– Refasten the airbox clips, re-attache the air duct and plastic pins. You’re almost done.

– AEM filters come with an AEM logo decal. This is useful to stick on your airbox (or wherever you like) to let your oil change service know that they need not even open the airbox because you have a re-usable filter. Save $20. I put mine right on the airbox cover. Clean and dry the airbox location before applying the decal, of course, so it sticks and stays. I just used Windex (my car is less than a month old) but rubbing alcohol is probably a better choice if your car has had time to build up more grime on the airbox.

As for performance and engine sound:

– I believe it does actually smooth things out between gears a bit, as has been mentioned, and i think the added throttle response is noticeable (but not dramatic) from around 3,000 RPM and above. Did a high-speed freeway test earlier tonight (cool summer air, around 72 degrees F, which turbo likes anyway) and it felt like i was never starved for air in the higher RPM range; there was just always power on tap, whatever i asked the car to do. Then again, it is a WRX. 😉

– Engine sound: extremely subtle change, most people will probably never notice. Assuming it’s not my imagination, i do think there was a subtle new engine note, again mostly surfacing around 3-4,000 RPM, that filled out the midrange with a warm, slightly fuller frequency, but — sorry, this won’t really give you an increased throaty low like some intakes i’ve used in the past. The WRX is already pretty good at throaty lows anyway…

Hope this helps someone. I’ll give one more nod to the reviewers that came before me, whose reviews gave me what i needed to make a call on this product. Ignore the plebs, this works in a Base/Premium/Limited 2.0L WRX.

So far so good! Installed this in my 2015 Subaru Legacy 2.5 and yes it does fit just fine! There is a top and you need to line it up properly unlike some people say. The filter in this engine is not square even though it almost looks like it. I love being able to clean this rather than just having to replace filters. I can clean it more often than I would replace a normal filter so I will always have a clean filter. Engine sounds a little more free breathing, slight bump in highway MPG, and it might accelerate nominally better….but what you’re really getting from this is the ability to just clean and put it back in rather than having to buy a new filter and chuck the old one in the bin.

Seals way better than the Fram filter it replaced – gone is the additional intake noise.
Didn’t notice any additional performance, but having a nice, reusable filter is all I wanted to get out of this (and get rid of the intake noise, seriously that Fram filter was bad).