E9x M3 K&N drop-in Air Filter

This is absolutely the least expensive and easiest way to improve horsepower and extend the life of your air filter! The sandwiched layers of cotton gauze, specially treated with K&N air filter oil, provides five times more filtering surface over the element circumference. This serves to smooth incoming air flow while reducing intake restriction and thereby boosting horsepower. K&N Performance Air Filters come pre-oiled for easy installation and with K&N's famous 1,000,000 mile warranty. K&N filters are easy to clean: wash with cold water every year and re-oil it every two years for a lifetime of performance.

K&N Replacement Automotive Air Filters

• Designed to Increase Horsepower & Acceleration
• K&N Million Mile Limited Warranty�
• Washable and Reusable
• Will NOT Void Vehicle Warranty
• Lasts up to 50,000 miles before cleaning is required depending on driving conditions
• Emissions Legal in all 50 US States.
• Economical, a K&N Air Filter Will Last the Life of Your Automobile, Motorcycle, or ATV
• Works with Vehicle Electronics
• Environmentally Friendly
• Replaces factory stock air filter
• K&N Air Filters - Designed to Increase Horsepower & Acceleration

Since 1969 K&N Engineering has been designing, manufacturing, and enhancing High-Flow Air Filters for the automotive and motorcycle enthusiast interested in maximizing horsepower and acceleration.  Since our humble beginnings we have designed and manufactured over 2,400 High-Flow Air Filters to fit most modern passenger vehicles and over 500 High-Flow Air Intake Systems to fit vehicles driven by enthusiast minded drivers.  We not only have more applications than any other manufacturer of similar product, we invented the High-Flow category and the High-Flow Technology that supports it.  K&N also makes thousands of racing and specialty type air filters and is the #1 Filter in NASCAR�.

Anyone can flow more air.  The trick is to flow more air safely.  In our opinion we hit the sweet spot _ an optimal blend of high air flow, filtration efficiency, durability and dust capacity.  We take filtration seriously.  K&N Air Filter media has been tested both in-house and by independent labs using the ISO5011 test developed by the Society of Automotive Engineers.  In addition we test many of our filters both in and out of the OE airbox ensuring proper fit and function.  Our goal is to design filters with the maximum possible airflow achievable while providing guaranteed engine protection.

A K&N Air Filter is made of 4 to 6 layers of cotton gauze sandwiched between two epoxy-coated aluminum wire screens.  The cotton is treated with a specially formulated grade of oil causing tackiness throughout the cotton�s microscopic strands.  The nature of the cotton allows high volumes of airflow, and when combined with the tackiness of the oil creates a powerful filtering media that ensures engine protection.  In contrast, most other media can not maintain the same balance of airflow and filtration throughout the filter's life without sacrificing one or the other.  With a K&N Air Filter, there is no sacrifice.

K&N uses independent laboratories to help ensure that our products meet or exceed your high performance and high filtration demands.  Better yet, we conduct our own testing at our own state-of-the-art in-house testing laboratory.  For more information on K&N air filters and testing go to the K&N Technical Learning Center area.  K&N�s dedication to providing a first-class air filter can also be seen outside the testing laboratory. Consider that K&N has sold more than 20 million air filters since 1969. One such filter was put in the airbox of a three-quarter ton Chevy pickup and driven more than one million miles by Carl Judice of New Iberia, Louisiana. Carl points out that he has never rebuilt the engine, nor removed the cylinder head from his trusty pickup truck. Real world testing and customer satisfaction doesn�t get any better than that.

Handmade in the USA and in the United Kingdom using only the finest materials, K&N OE Replacement Air Filters are washable and reusable.  Regardless of what you�ve heard, it�s almost impossible to wash your K&N Air Filter too much.  Inside our testing laboratory, we have washed and re-oiled one K&N Air Filter more than 100 times and it still performs up to specification.  Depending on your driving conditions, we recommend cleaning your air filter every 50,000 miles.  To clean and re-oil, purchase our filter Recharger� service kit and follow the easy instructions.

Fuel economy testing and mileage claims are a tricky business. Just ask the EPA, whose website states, "EPA�s fuel economy estimates are designed to allow consumers to comparison shop.  Your fuel economy will almost certainly vary from EPA�s fuel economy rating.  This is based on a number of factors, such as weather, road conditions, your driving and maintenance habits, and your use of air conditioning."  A lot of exaggerated claims are made in the marketplace by products claiming to improve gas mileage.  K&N makes no general fuel economy claims, however we encourage you to try our air filter for yourself.  Keeping air filter restriction as low as possible can be an important tool, among others, for maintaining high mileage.