How to install a K&N Drop-In Replacement Air Filter on your Mustang

Congratulations, you have purchased the finest air filter that money can buy. With proper care, this filter will last 1 million miles or more. This filter is a direct replacement for the stock air filter, and no modifications will be required. This air filter does not require a specific installation procedure; however, if you do experience difficulties with the fit of your K&N® air filter, check below for some common tips to help you. Everyone’s mechanical ability is different; if you are unsure on how to correctly change your air filter please seek a professional mechanic’s help.

• Verify that you have the correct filter that is listed in the K&N® catalog for your make, model, year and engine size. Vehicle manufacturers can change air filter housings from one year to the next and from model to model. Even though they may use the same OEM air filter, the K&N® air filter that was listed for one year or model may not fit or seal correctly; e.g.: Ford Taurus SHO uses the same OEM air filter as the 86-93 Mustang GT, but the K&N® 33-2015 for the Mustang will not fit the Taurus SHO. The 1989-1995 Taurus SHO must use a K&N® 33-2040.
• Disconnecting the air intake tube from the air box lid can make it easier to maneuver the lid. Some intake tubes are very rigid and do not bend or twist easily.
• Some K&N® air filters need to be installed into the air box lid first. This is due to the difference in manufacturing techniques of K&N® air filters. When installing the filter into the lid, hold the air filter in place with your index fingers while reinstalling the air box lid. This helps to prevent the air filter from falling out.
• On cars like some BMW’s and the Porsche Boxster that use a tray type air box, hold the air filter in place with your index fingers while inserting the cartridge into the air filter housing to prevent the filter from falling out of the tray. If your vehicle has the tray type air box and you have trouble pushing the lid closed try lubricating the back side of the tray with K&N® air filter grease or equivalent. This will reduce the friction between the air filter tray and the air box housing.
• Always make sure that the air filter is seated into the groove on the lid and that the lid is properly seated onto the air box base. If the filter, lid and base are not lined up correctly and you try to fasten the clips or screws that hold the two halves together you will most likely break the air box. Sometimes it will help if you gently slide the air box lid from side to side along the surface of the air box base until you feel the air box lid seat onto the base. Please note that the pressure needed to fasten the clips with a K&N® air filter will be slightly more than with an OEM type that has a soft foam seal. If the pressure needed seems excessive or you see the air box bending excessively - STOP and re-check your installation.
• Sometimes the screws or clips on an air box can fall off when changing or cleaning an air filter. If you do not have all of the screws or clips, the air filter might not seal properly, allowing dirt and dust to pass by the air filter and go straight into your engine. If you have some that are missing, you should get replacements from your dealership.
• On air boxes that use a type of hinge to fasten one side of the air box it helps to lightly coat the sealing surface with air filter grease or silicone spray. This reduces the friction that you might encounter when closing the air filter housing. Always make sure that the tabs on the lid or base are fully seated into the slots on the lid or base otherwise the air box could pop open while driving.
• Vehicles used in severe dust conditions (most of the southwestern states) will benefit from a generous application of K&N® air filter sealing grease on the filters sealing surface for extra protection.
• Some vehicles are equipped with a charcoal barrier that is riveted or otherwise built into the air box. This barrier may look like a secondary air filter, but it is actually part of the emissions system and should not be removed. This K&N® stock replacement filter is a drop-in filtration unit and does not require any modifications to your stock air cleaner system.