K&N 77-2578KS

Intake Kits > Performance Intake Kit
List Price: $551.11
Your Price: USD $303.99

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The K&N 77-2578KS high-flow performance air intake system is a free-flowing, mandrel-bent aluminum tube air induction system designed to fit some Ford Flex models. The restrictive factory air filter and air intake housing on your vehicle are replaced by this K&N air intake system which is designed to dramatically reduce air flow restriction as it smoothes and straightens air flow. The improved air flow allows your engine to inhale a larger amount of air than it would from the stock air intake. More air means more usable power and acceleration throughout your engine’s RPM range. The 77-2578KS air intake comes with a chrome topped K&N high-flow air filter and a heat shield that installs into the previous air box space. Air is directed through the intake tube into the engine’s throttle body for a guaranteed power gain. The intake tube has an attractive silver powder-coat finish that's made to last and it accommodates the factory mass air sensor, crank case vent hose and a replacement silicone EVAP hose. The oversized cone shaped air filter can be used for up to 100,000 miles before servicing is needed depending on driving conditions. This air intake is relatively easy to install usually in 90 minutes or less using existing factory mounting points. The tools needed are a screwdriver, pliers, ratchet set and some wrenches. Some K&N 77 series air intakes are not legal for sale or use in California and other states adopting California emission standards while others are CARB exempt and 50 state legal. Check the K&N catalog or website for vehicle applications and specific CARB status for each vehicle and air intake.

[More Information on K&N 77 Series Air Intake Systems]
  • Guaranteed to increase horsepower
  • Designed to improve throttle response and engine sound
  • Free-flowing aluminum tube
  • Replaces entire factory air intake system
  • Lasts up to 100,000 miles before service is required (depending on driving conditions)
  • Easy to install, usually in 90 minutes or less
  • Washable and reusable lifetime air filter
  • K&N Million Mile Limited Warranty

Product Specifications

Estimated Horsepower Gain9.19 HP @ 4914 RPM
Air Filter ColorRed
Air Filter Height6 in (152 mm)
Air Filter Large End Diameter7.5 in (191 mm)
Air Filter MaterialCotton Gauze
Air Filter Outlet ShapeRound
Clamp MaterialStainless Steel
Clamp StyleRegular
Clamps Included5
Couplers Included2
Intake Pipe Color / FinishSilver
Intake Pipe MaterialAluminum
Product Box Height12.5 in (318 mm)
Product Box Length22.25 in (565 mm)
Product Box Width14.25 in (362 mm)
Product Style77 Series Kits
Replacement FilterRF-1048
Street Legal In All US StatesYes
TUV Approved (Europe)No
Weight10.5 lb (4.8 kg)
Horsepower gains based on similar vehicle dynamometer test. Results will vary.

Customer Feedback

Be the first to review part 77-2578KS
Good product...worked well on my ford...just put this product on my Chevrolet and can't tell a difference...actually believe I lost power.

Jared Tyndal
Kenansville, NC
Wow I can't believe how good this air filter is. I drive a 2014 Ford Focus Hatch automatic with dual clutch transmission. I bought this air filter based on the recommendation of a friend. I really can't believe what a difference this air filter has made in my vehicle. This air filter has great improved my low end torque and acceleration. It has not made into a sports car but there definitely is a noticeable improvement. Periodically I would get that transmission stutter from the dual clutch transmission, not often but once in a while. With this new air filter I have not experienced that once. This air filter has worked so well I am thinking of investing in the air intake system for $299. There is no reason you shouldn't have on of these filters in your car. A life time part for $60. Instead of paying $20 every 10,000 miles. This really is a no brainer.

Boston, Massachusetts
The K&N cold air intake kit is great on my 2005 Ford Explorer. I ordered the kit about 2 years ago. I pull a heavy trailer. The explorer is barely big enough to pull it. Installing this kit is a BIG help in letting the engine breathe. It sounds great and makes me feel better too, putting this load on my car. The installation was straight forward and the instructions were excellent. The installation was no problem. Only 2 minor issues. The airflow sensor mounting pad had a casting lap that deformed the mounting surface. I was able to smooth it out with a sharp knife and light sanding. The other issue was that I mounted the filter such that it was riding hard on the bottom of the intake box. This was my fault. I didn't find out until I took the filter off to clean and re-oil it and found a very small worn spot on the filter. When I install this new filter I will make sure that the filter is free from interference all around. Thanks for a great product I'll be using K&N from here on out.

Phil Kirby