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K&N is the inventor of the Air Intake System and has over 50 years of experience in the performance filtration industry. Proudly designed and manufactured in the USA, this premium cold air intake system is specifically designed for your vehicle and is dyno tested to provide a guaranteed increase in horsepower. It features a high flow intake tube, custom heat shield, and oversized K&N Washable High-Flow Cotton Air Filter for ultimate airflow. This Intake system replaces the restrictive OEM air box to provide an improved driving experience for daily driving or towing. It installs easily in about 60 minutes and is backed by a No-Hassle Lifetime Limited Warranty and will not void your factory warranty. Legal for use in all 50 states.
Compatible Vehicles:
- 2004-2008 FORD F150
- 2006-2008 LINCOLN Mark LT
- 2005 FORD Expedition
Amazon.com
Designed to provide increased horsepower, the K&N 57-2556 Second Generation Fuel Injection Performance Kit is a quick solution for vehicle owners who are looking for an increase in reliable power. Street legal, installable in 90 minutes or less and built around K&N's High-Flow technology, which utilizes a special oversized and washable cotton gauze air filter and special cold air intake, nonmetallic tubes, the 57-2556 drives a massive amount of air into an engine, which translates into power affordable on virtually any budget. .caption { font-family: Verdana, Helvetica neue, Arial, serif; font-size: 10px; font-weight: bold; font-style: italic; } ul.indent { list-style: inside disc; text-indent: -15px; } table.callout { font-family: verdana; font-size: 11px; line-height: 1. 3em; } td.vgoverview { height: 125px; background: #9DC4D8 url(https://images-na.ssl-images-amazon.com/images/G/01/electronics/detail-page/callout-bg.png) repeat-x; border-left: 1px solid #999999; border-right: 1px solid #999999; padding-left: 20px; padding-right: 20px; padding-bottom: 10px; width: 250px; font-family: verdana; font-size: 12px; }
Affordable, street legal horsepower upgrade.
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Measurable improved performance.
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Quick and easy installation.
. How High-Flow Technology Works
How does the K&N 57-2556 increase horsepower? By eliminating airflow obstruction in your engine. Restriction of air flow between an air filter and an engine robs even the most powerful engine of horsepower. K&N air intake kits virtually eliminate air path restriction by replacing the standard air filter and the entire air path to the engine. The aerodynamically engineered conduit that makes up the 57-2556 drives a massive amount of air into an engine, which translates into power. This conduit begins with an oversized conical high-flow air filter. This larger filter can fit into the engine compartment using factory holes and mounting points because the K&N 57-2556 replaces your stock intake tube, and air box. This provides more airflow at lower restriction than a standard filter, limited by the size of the factory air box. The oversize air filter also captures and holds more dirt, increasing the service life before a cleaning is required (up to 100,000 miles). The filter is also isolated from high engine temperature by a heat shield designed to lower the temperature of the air entering the engine, which increases horsepower.
The filter attaches to a rotationally molded tube made from nonmetallic interlaced high density polyethylene (HDPE). This allows for precision shaping of the tube to reduce turbulence and accelerate airflow into the engine. This is why some K&N tubes have unique shapes or indentations that are specifically engineered for each engine configuration. Finally, the tube is connected to the engine with adapters made from high strength materials such as silicon and reinforced nylon and ensures long life. Put all this together and you have the best high-flow intake system available today.
Street Legal
Many K&N intake systems are street legal in all 50 states and include a California Air Resource Board (CARB) Executive Order (EO) number that ensures the kit has been tested to comply with emissions standards. EO numbers apply to the kit as well as the year, make and model it is being installed on. Systems with no EO number are street legal in most states but may not be used on emissions controlled vehicles in the state of California or other states adopting California emission standards. Consult K&N's website to search by part to see which cold air intakes are CARB exempt for which vehicles.
Key Features:
- Guaranteed to provide increased horsepower and acceleration (15.47 hp @ 3,829 rpm measured by manufacturer).
- Engineered to specific vehicle design. See vehicle search above for compatibility.
- Easy to install, usually in 90 minutes or less and lasts up to 100,000 miles before service is required, depending on driving conditions.
- CARB exempt and street legal in all 50 US States.
- Air filter is washable and reusable for extreme durability, but can also be easily replaced if necessary.
- Works with original manufacturer computer systems.
- Replaces OEM filter and air box, and is designed to use factory holes and mounting points whenever possible.
- Million mile limited warranty.
1-K&N 57-2556 Second Generation Fuel Injection Performance Kit (includes air intake tube, washable air filter, heat shields, hoses, hose clamps, hardware and detailed instructions necessary for installation).
Limited Warranty
K&N O/E replacement air filters and air intake systems purchased from authorized dealers are backed by a million mile limited warranty from the manufacturer when used primarily on paved roads and on vehicles for which they were designed. If one of these products ever fails to provide complete satisfaction, K&N will replace it at their discretion.
About K&N Engineering
K&N Engineering, of Riverside, California, is the inventor and leading innovator of reusable cotton gauze filter technology for automotive applications. From humble beginnings as a family run business over 35 years ago, K&N Engineering, now a truly global company with offices in the UK and the Netherlands, continues to exist as a family owned business with an enthusiast mindset and a direct connection with motor sports that carries over throughout all levels of management and manufacturing.
* Note: Some FIPK's will not fit on vehicles with lift kits. Diesel pickup truck performance intakes for Power Stroke, Duramax and Cummins Engines are also available.
Customer
2025-08-21 15:59:21
This was an easy install, only took 1.5 hours. Some F150’s you’ll need a 1/8th drill bit to drill a hole for a mounting bracket, fortunately I already had the hole in mine. You do need some specialized tools but can ultimately get by without. Immediately noticed an increase to power and acceleration. It’s also considerably louder and sounds fantastic. Frees up alot of engine space and looks great. I’d consider this a must buy for the 5.4l Triton V8. I have a 2006 F150 Lariat Supercab 4x4 for reference. I’d also pay more and buy the metal version, I’ve heard stories of the plastic cracking after a couple of years. I’d also follow the K&N instructions and not youtube videos as alot of youtube videos are referencing the older model where you needed to remove the throttle body. This version you do not need to remove the throttle body.
CatMeister
2025-08-16 13:00:25
Actually just installed this product yesterday on my 2004.5 F150 Lariat with 5.4 Triton. Whole process took about 1.5 hrs. or so. Instructions were pretty decent with two exceptions:1) Was instructed to remove the overflow hose from radiator to overflow tank. Presumably because it would be too short or otherwise in the way. This required getting a bucket to catch liquid from top of radiator & about 7-8 min. to swap out. It turned out to be totally unneeded. The existing hose could have stayed exactly the way it was. In fact, the replacement hose is more in the way as it is not contoured to go around the filter/heat shield box as well as the existing one was.2) After mounting the air tube/filter through the heat shield near the end of install, noticed that there was a large open gap around that tube. Didn't make sense as heat/dirt could easily get through & it seemed incomplete. So, I took the remaining piece of excess rubber "edge trim" (that goes on top/side of heat shield) & installed it around the inside edge of the round opening for the tube in the heat shield. Worked like a charm to seal that gap. Although, they don't tell you to do it, it totally makes sense.After install, took a long ride to check it out. There was a definite change with the throaty sound when accelerating & a slight kick in the responsiveness. After a second longer drive a bit later, the sound & acceleration improved a bit more. Perhaps the engine computer/mass air sensor had to adjust to the change - it seemed to run even better after the second drive. Hasn't been long enough to check on the mpg as yet. But, when I did the same installation on another car of mine, it did make roughly a 1.5 mpg increase.I'll say that it sure makes more room under the hood. And, it looks much better with all that excess plastic bulk removed. On a side note, some reviewers complained of a "whistling" noise from this unit. I have heard no such noise at all. Perhaps, their install was just a bit off. Or, maybe my closing that gap around the air tube makes a difference. Not sure but, mine sounds and performs great - just as it was advertised.Noticed that the only two negative reviews both had the same 2006 models and the same issues. Perhaps, that is not a coincidence. I also noticed that they both generally only give negative reviews...just sayin.Nonetheless, I would definitely recommend this to others for their Ford truck.UPDATE: Have checked gas mileage a couple of times after install on road trips. Have come to conclusion the FIPK added maybe 1-1.5 mpg at most. I think alot of people don't notice any increase or perhaps even a slight decrease in mpg as they keep "their foot in it" to hear the cool sound & experience the HP increase. Just an opinion - I am totally satisfied with the purchase.
LoganMC
2025-08-11 19:49:00
I sought after this one because of it being all black and simple looking to install and boy was it the right move... looks and functions amazingly...bolted right up.throttle response is great, cant say touch on the MPG's I'm saving cause I swapped a fuel control module along with the intake, but it's just another good K/N. They could work on the price though...
Roger T.
2025-08-10 18:15:39
The Intake and filter itself are fantastic. I installed it on my 06 F150 5.4L and it sounds really deep and mean when I'm at about 3k RPMs. The only reason I took off a star was because of the instructions. In the steps it will say something like "install the bracket with the included hardware". This is a problem for me because the included hardware is a bunch of bolts, washer, nuts, etc in one bag. Nothing is labeled and the instructions do not say to add a washer to anything or which bolt go where. The only thing it says remotely close to that is one diagram on the first page that has a breakapart of the whole intake with the parts labeled. This diagram is pretty small so it may be hard for some people to see every part. I ended up getting it on my vehicle and it is running so hopefully everything went in the right spot. If the instructions could be a little more clear like "install a 6mm bolt and washer into the two brackets on the housing" or something along those lines it would have been an easy 5 star review for me.
Steve
2025-08-09 12:17:25
I would like to preface this review by noting that I did not install the piece myself but I had Express Oil do it. Even so, I still paid less for the part and installation than the prices that other websites offer the same filter. The worker said he had to glance at the installation guide once to see why they gave an extra cable but other than that he said it was pretty simple.I drive an F150 FX4 5.4. Liter. It already had an extremely loud exhaust on it. As soon as I left the parking lot with my new intake, I could tell a difference. Acceleration felt smoother, the exhaust sounded cleaner, and listening to the intake suck in air when you press the gas is awesome. I don't see that getting old any time soon. I'm not sure on gas mileage yet but I will be updating my review in a month or so when I can give more information.My girlfriend even noticed that my truck has a cleaner sound and feel to it. My idling exhaust is much smoother, but when I gun it, I'd swear its twice as loud and twice as fast. There seems to be a much better throttle response like others have noted. It used to be that there would be a delay from my foot smashing the gas pedal to the engine responding. Now, it's almost instantaneous.I highly recommend this product to any one. If you're still debating it, go for it! You've got nothing to loose and 15 hp to gain! I hope this review helps some people.***will update on mpg as soon as possible.
West Coast Woodsy
2025-07-23 19:44:10
Definitely improved my 08 F150. 5.4 Triton. It was relatively easy to install. I am missing a couple of bolts from the pack. I managed to get by, but the plastic plugs for the intake, they’re garbage. They just strip the threads too easily. If you don’t know your way around an engine, you might not want to attempt installing this.
C.B.
2025-07-20 10:18:58
I replaced my factory Intake with this model after looking at several alternatives and doing a bit of research. It was fairly easy to install, however you may want to follow the install video on Youtube as the supplied instructions aren't great.The product itself once installed did what it promises. While I have no way to see if it actually increased my horse power my truck does seem to have more punch off the line and seems to pull my trailer easier than before. The one thing I really noticed was the increase in my gas milage, It ranges from around 3 - 5 l/100km better than with my old intake. Last thing to mention, it is loud, when operating at higher RPM's it almost deafening, I really like the throaty sound it makes while when accelerating, it's not bad at all, but when it's a constant while pulling at trailer into a really high wind it's a little much, it did pull great but if your doing a lot of heavy towing all the time this may not be the best option for you unless you have earplugs.Now I know there are sceptics out there and they and they may have a legit case, but all I can do is tell you is how it works for me and I'm impressed. Hopefully you are too.
Customer
2025-05-25 18:01:44
Product came fast to my door, fitment was excellent. Would buy again
Garry Hill
2025-05-24 16:20:44
It did exactly as promised plus it gave my truck a growl and jet motor sound I really wasn't expecting. Bonus!
Johnny Blaze
2025-05-06 13:51:58
Well it's K&N so if you're a brand whore this is what you want. The quality and construction of the materials is substandard to say the least they were missing Nuts and Bolts luckily I had a horde of them. For what this cost I definitely would have went with the Spectre cold air intake but the client wanted what the client wanted.
Customer
2025-05-03 11:15:57
This was an easy install, only took 1.5 hours. Some F150’s you’ll need a 1/8th drill bit to drill a hole for a mounting bracket, fortunately I already had the hole in mine. You do need some specialized tools but can ultimately get by without. Immediately noticed an increase to power and acceleration. It’s also considerably louder and sounds fantastic. Frees up alot of engine space and looks great. I’d consider this a must buy for the 5.4l Triton V8. I have a 2006 F150 Lariat Supercab 4x4 for reference. I’d also pay more and buy the metal version, I’ve heard stories of the plastic cracking after a couple of years. I’d also follow the K&N instructions and not youtube videos as alot of youtube videos are referencing the older model where you needed to remove the throttle body. This version you do not need to remove the throttle body.
CatMeister
2025-04-07 14:19:16
Actually just installed this product yesterday on my 2004.5 F150 Lariat with 5.4 Triton. Whole process took about 1.5 hrs. or so. Instructions were pretty decent with two exceptions:1) Was instructed to remove the overflow hose from radiator to overflow tank. Presumably because it would be too short or otherwise in the way. This required getting a bucket to catch liquid from top of radiator & about 7-8 min. to swap out. It turned out to be totally unneeded. The existing hose could have stayed exactly the way it was. In fact, the replacement hose is more in the way as it is not contoured to go around the filter/heat shield box as well as the existing one was.2) After mounting the air tube/filter through the heat shield near the end of install, noticed that there was a large open gap around that tube. Didn't make sense as heat/dirt could easily get through & it seemed incomplete. So, I took the remaining piece of excess rubber "edge trim" (that goes on top/side of heat shield) & installed it around the inside edge of the round opening for the tube in the heat shield. Worked like a charm to seal that gap. Although, they don't tell you to do it, it totally makes sense.After install, took a long ride to check it out. There was a definite change with the throaty sound when accelerating & a slight kick in the responsiveness. After a second longer drive a bit later, the sound & acceleration improved a bit more. Perhaps the engine computer/mass air sensor had to adjust to the change - it seemed to run even better after the second drive. Hasn't been long enough to check on the mpg as yet. But, when I did the same installation on another car of mine, it did make roughly a 1.5 mpg increase.I'll say that it sure makes more room under the hood. And, it looks much better with all that excess plastic bulk removed. On a side note, some reviewers complained of a "whistling" noise from this unit. I have heard no such noise at all. Perhaps, their install was just a bit off. Or, maybe my closing that gap around the air tube makes a difference. Not sure but, mine sounds and performs great - just as it was advertised.Noticed that the only two negative reviews both had the same 2006 models and the same issues. Perhaps, that is not a coincidence. I also noticed that they both generally only give negative reviews...just sayin.Nonetheless, I would definitely recommend this to others for their Ford truck.UPDATE: Have checked gas mileage a couple of times after install on road trips. Have come to conclusion the FIPK added maybe 1-1.5 mpg at most. I think alot of people don't notice any increase or perhaps even a slight decrease in mpg as they keep "their foot in it" to hear the cool sound & experience the HP increase. Just an opinion - I am totally satisfied with the purchase.
LoganMC
2025-04-05 13:08:42
I sought after this one because of it being all black and simple looking to install and boy was it the right move... looks and functions amazingly...bolted right up.throttle response is great, cant say touch on the MPG's I'm saving cause I swapped a fuel control module along with the intake, but it's just another good K/N. They could work on the price though...
Roger T.
2025-03-25 16:33:18
The Intake and filter itself are fantastic. I installed it on my 06 F150 5.4L and it sounds really deep and mean when I'm at about 3k RPMs. The only reason I took off a star was because of the instructions. In the steps it will say something like "install the bracket with the included hardware". This is a problem for me because the included hardware is a bunch of bolts, washer, nuts, etc in one bag. Nothing is labeled and the instructions do not say to add a washer to anything or which bolt go where. The only thing it says remotely close to that is one diagram on the first page that has a breakapart of the whole intake with the parts labeled. This diagram is pretty small so it may be hard for some people to see every part. I ended up getting it on my vehicle and it is running so hopefully everything went in the right spot. If the instructions could be a little more clear like "install a 6mm bolt and washer into the two brackets on the housing" or something along those lines it would have been an easy 5 star review for me.
Steve
2025-03-20 14:15:27
I would like to preface this review by noting that I did not install the piece myself but I had Express Oil do it. Even so, I still paid less for the part and installation than the prices that other websites offer the same filter. The worker said he had to glance at the installation guide once to see why they gave an extra cable but other than that he said it was pretty simple.I drive an F150 FX4 5.4. Liter. It already had an extremely loud exhaust on it. As soon as I left the parking lot with my new intake, I could tell a difference. Acceleration felt smoother, the exhaust sounded cleaner, and listening to the intake suck in air when you press the gas is awesome. I don't see that getting old any time soon. I'm not sure on gas mileage yet but I will be updating my review in a month or so when I can give more information.My girlfriend even noticed that my truck has a cleaner sound and feel to it. My idling exhaust is much smoother, but when I gun it, I'd swear its twice as loud and twice as fast. There seems to be a much better throttle response like others have noted. It used to be that there would be a delay from my foot smashing the gas pedal to the engine responding. Now, it's almost instantaneous.I highly recommend this product to any one. If you're still debating it, go for it! You've got nothing to loose and 15 hp to gain! I hope this review helps some people.***will update on mpg as soon as possible.
West Coast Woodsy
2025-03-16 12:18:02
Definitely improved my 08 F150. 5.4 Triton. It was relatively easy to install. I am missing a couple of bolts from the pack. I managed to get by, but the plastic plugs for the intake, they’re garbage. They just strip the threads too easily. If you don’t know your way around an engine, you might not want to attempt installing this.
C.B.
2025-02-19 15:33:17
I replaced my factory Intake with this model after looking at several alternatives and doing a bit of research. It was fairly easy to install, however you may want to follow the install video on Youtube as the supplied instructions aren't great.The product itself once installed did what it promises. While I have no way to see if it actually increased my horse power my truck does seem to have more punch off the line and seems to pull my trailer easier than before. The one thing I really noticed was the increase in my gas milage, It ranges from around 3 - 5 l/100km better than with my old intake. Last thing to mention, it is loud, when operating at higher RPM's it almost deafening, I really like the throaty sound it makes while when accelerating, it's not bad at all, but when it's a constant while pulling at trailer into a really high wind it's a little much, it did pull great but if your doing a lot of heavy towing all the time this may not be the best option for you unless you have earplugs.Now I know there are sceptics out there and they and they may have a legit case, but all I can do is tell you is how it works for me and I'm impressed. Hopefully you are too.
Customer
2025-02-15 18:17:45
Product came fast to my door, fitment was excellent. Would buy again
Garry Hill
2025-02-12 11:09:19
It did exactly as promised plus it gave my truck a growl and jet motor sound I really wasn't expecting. Bonus!
Johnny Blaze
2025-01-29 13:28:36
Well it's K&N so if you're a brand whore this is what you want. The quality and construction of the materials is substandard to say the least they were missing Nuts and Bolts luckily I had a horde of them. For what this cost I definitely would have went with the Spectre cold air intake but the client wanted what the client wanted.
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