K&N® 33-2304 - 33 Series Panel Air Filter

53 reviews / Item # mpn1921658
K&N® - 33 Series Air FilterK&N® - 33 Series Air FilterK&N® - 33 Series Air Filter Installation InstructionsK&N® - 33 Series Air Filter Airflow TestK&N® - Cleaning GuideK&N® - Air Filter Overview 602x420K&N Authorized DealerK&N Special OffersK&N Special OffersK&N Special Offers
● In Stock (578) - Usually ships within 24 hours
Vehicle Specific
Fits Following Model(s):
  • Please Select Vehicle Below
Select Vehicle
Add To Cart
Have a Question? 800.505.3274
Ask a Specialist: Live Chat
Authorized Dealer:K&N
Lowest Prices. Price match guarantee
Guaranteed Fitment. Always the correct part
In-House Experts. We know our products
Easy Returns. Quick & Hassle Free
Select VehicleSelected Vehicle

Product Details

Learn everything you want to know about this product
to make an informed purchase.

K&N Air Filters

33 Series Panel Air Filter (33-2304) by K&N®. A K&N 33 series OE replacement air filter is designed to increase horsepower and acceleration. These washable and reusable panel air filters are easy to install because they fit directly into the existing vehicle factory air box.

K&N - F.A.Q.K&N - Air Filter CleaningK&N - Warranty


  • Improves engine airflow
  • Increases horsepower and acceleration
  • Superior filtration without reduced airflow
  • Reduces maintenance costs
  • Washable and reusable
  • Get up to 50,000 miles between cleanings under normal driving conditions
  • Emissions legal in all States
  • Backed by K&N's Million Mile Limited Warranty

Most air filters on the market are a compromise. Many high-performance filters deliver better airflow, but sacrifice filtering ability and engine protection in the process. OEM filters, which are usually made of paper, filter adequately but at the expense of airflow. And airflow decreases as these air filters become dirty. Not so the K&N air filter. K&N air filters increase airflow without decreasing filtration ability, and the increased airflow remains consistent throughout the filter's service interval. The secret is in the K&N filter's construction.

K&N's initial goal was to develop a filter that would deliver increased airflow during dirty, dusty off-road racing conditions. Increased airflow improves the efficiency of the combustion process, increasing horsepower and torque. But just increasing airflow without ensuring adequate filtration under those conditions would result in a ruined engine. K&N's solution was a filter design consisting of 4 to 6 layers of cotton gauze sandwiched between two aluminum wire screens. The cotton is then treated with a specially formulated grade of oil that causes tackiness throughout the cotton’s microscopic strands. The resulting K&N filter not only delivers increased airflow while trapping dirt particles that could harm your engine, that level of airflow is maintained even as the filter gets dirty. The layers of oiled cotton fibers in the K&N filter trap dirt particles that are smaller than the holes in the filter media. The thickness of the layers also allows the K&N filter to trap dirt and dust on many levels, trapping more dirt without decreasing airflow. Contrast this with a paper filter that only traps dirt on its surface; as the surface area becomes clogged, the airflow rate goes down.

Each K&N air filter is custom designed to fit into your existing factory air box. The K&N filter is economical because it's the last air filter you'll have to buy for your car. It can be washed and reused many times, and since you can usually drive up to 50,000 miles between servicing, you won't have to clean it very often. And every K&N filter is backed by K&N's Million Mile Limited Warranty. By the way, check the CARiD reviews and read what the customers think of K&N porducts.

K&N® is the inventor and leading innovator of reusable cotton gauze filter technology for automotive applications. The first K&N filter was conceived for racing over 40 years ago and a performance enthusiast mindset continues today throughout all levels of the company. K&N is the sales and brand leader for performance filters, including an extensive line of factory replacement filters and performance air intake kits. The company actively promotes the environmental, economical and performance advantages of long-life reusable cotton gauze filters.

Part Number:

Vehicle Fitment

This part is compatible with 56 vehicle(s)
Year Make Model Fitment Notes:
2016 Subaru WRX / WRX STI
2015 Subaru Forester
2015 Subaru Impreza
2015 Subaru WRX / WRX STI
2015 Subaru XV Crosstrek
  • Limited / Premium / Sport / Touring
2014 Subaru Forester
2014 Subaru Impreza
2014 Subaru Legacy
2014 Subaru Outback
2014 Subaru Tribeca
2014 Subaru WRX
  • Base / Limited / Premium
2014 Subaru WRX STI
  • Base / Limited
2014 Subaru XV Crosstrek
  • Limited / Premium / Sport / Touring
2013 Subaru Forester
2013 Subaru Impreza
2013 Subaru Legacy
2013 Subaru Outback
2013 Subaru Tribeca
2013 Subaru WRX STI
  • Base / Limited
2013 Subaru XV / XV Crosstrek
2012 Subaru Forester
2012 Subaru Impreza
2012 Subaru Legacy
2012 Subaru Outback
2012 Subaru Tribeca
2012 Subaru WRX / WRX STI
2011 Subaru Forester
2011 Subaru Impreza
2011 Subaru Legacy
2011 Subaru Outback
2011 Subaru Tribeca
2011 Subaru WRX / WRX STI
2010 Subaru Forester
2010 Subaru Impreza
2010 Subaru Legacy
2010 Subaru Outback
2010 Subaru Tribeca
2010 Subaru WRX / WRX STI
2009 Subaru Forester
2009 Subaru Impreza
2009 Subaru Legacy
2009 Subaru Outback
2009 Subaru Tribeca
2009 Subaru WRX / WRX STI
2008 Subaru Impreza
  • 2.5i / Outback Sport / Sport
2008 Subaru Legacy
  • 2.5L / 3.0L
2008 Subaru Outback
2008 Subaru Tribeca
2008 Subaru WRX / WRX STI
2007 Subaru Legacy
2007 Subaru Outback
2007 Subaru Tribeca
2006 Subaru Legacy
2006 Subaru Outback
2006 Subaru Tribeca
2005 Subaru Legacy
2005 Subaru Outback
Show all vehicle fitments

Product Reviews


Every Customer can leave a review about our service and the product that was purchased. In order to leave your review for your new product, please follow the link in the email you receive after completing your purchase. You can rate appearance, ease of installation, price/value and product quality.

K&N® - 33 Series Air Filter
K&N® 33-2304 - 33 Series Panel Air Filter
Average Rating: 4.9 of 5
4.8 of 5
K&N® 33-2304 - 33 Series 33 Series Air Filter
2015 Subaru WRX / Posted by (Tampa, FL) /

K&N came as described. Easy to install.

Was this review helpful for you? Yes
5 of 5
K&N 33 Series Air Filter
2011 Subaru Legacy / Posted by (Bellevue, NE) /

Initially noticed an almost 2 mpg increase before the computer adjusted to the new airflow. Now, the gas mileage is back to normal, but there is a bit more power.

Was this review helpful for you? Yes4   people found this review helpful.
5 of 5
K&N Air Filter
2011 Subaru Outback / Posted by (Clayton, NC) /

Great value and bump in both performance and mpg. I always install these type filters in my vehicles. Helps your engine to receive proper amount of air to provide enhanced performance. They really do pay for themselves in just a couple of years of use.

Was this review helpful for you? Yes4   people found this review helpful.
K&N® - 33 Series Air FilterK&N® 33-2304 - 33 Series Panel Air Filter    $47.99
53 reviews
Add To Cart