K&N 63 Series Air Intake Kit Review

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When it comes to air intake kits, K&N is like Coca Cola. Everybody who’s ever talked about performance knows about K&N. They invented the re-usable cotton gauze air filters that have been the basis of every performance air filter and air intake since they went into business 35 years ago. K&N literally founded the market for performance air intakes and filters, and they deserve a lot of credit for bringing proper engine breathing to the forefront of the consumer’s mind.

We were invited to test both K&N’s performance air filter and their 63 series air intake, and if you follow this site closely you’ll know that the K&N performance air filter passed our tests with flying colors and received our whole-hearted endorsement. Yet it’s hard for us to make the same recommendation about K&N’s 63 series air intake.

View of installed air intake.

The K&N 63 series intake installed in a 2007 Toyota Tundra with the 5.7L.

First of all, the kit itself and the install process were unduly complicated. K&N’s 63 series is unlike the factory air box or the Volant and aFe kits we tested. Instead of placing a high performance filter in a custom made air box, K&N asks you to strip away the factory air box and replace it with a carefully bent piece of punched sheet metal, some brackets, some clamps, some weather stripping, a tube, hardware, and a nice filter that you assemble yourself.

Some assembly is required.

K&N’s 63 series air intake requires quite a bit of assembly prior to installation, especially when compared to similarly priced kits from aFe and Volant.

To install the air intake, you have to build it first. You take the two pieces of weather stripping and tediously slide them onto the inside and outside edges of the sheel metal that separates the intake from the engine. Then, once you’ve completed that step, it’s time to bolt down four separate brackets that attach the sheet metal separator to the truck. There’s also a funny looking air tube support that must be placed in the engine compartment just so. Finally, you have the more familiar install steps like pulling the MAF out of the stock air box and installing it in the new kit.

Front view of separator. Side view of separator.

The separator requires four different brackets to be installed in order to make sure it’s secure. The ‘K’ in K&N is for ‘Komplicated.’

Installing the hose clamps is a complicated process too – or at least it must be, because the air filter fell off the air tube on our test unit (during the middle of a hill climb with trailer, no less). Either we didn’t get it tight enough or the clamp loosened up on us.

Without going on and on about the install process (maybe it’s too late?), let’s just say the ‘K’ in ‘K&N’ stands for ‘Komplicated.’ We could install two or three air intake kits from aFe or Volant in the time it takes to install one intake kit from K&N. Even worse, it’s hard to imagine how K&N’s “some assembly required” kit costs the same or more than kits from aFe and Volant. It seems that you should get some sort of discount for doing all the labor yourself. At least the instructions were clear and well illustrated…

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Installing the K&N Series 63 air intake is more complicated and time consuming than competitive intakes.

When it comes to fit and finish, we’ve got another bone to pick. K&N’s kit requires that you tediously install weather stripping into the inside hole of the separator. It would seem that the purpose of this would be to block warm engine air from passing by the separator and entering the filter, yet there’s a significant gap between the tube and the hole in the separator. The gap between the tube and the hole varies between 1″ and 2″ wide all the way around. Not only is this disappointing to realize after you’ve spent all that time installing weather stripping, it’s also hard to understand why K&N didn’t make the design a little better. We asked our contact at K&N about this and he explained that they need a gap to accommodate vibrations. That seems, at best, a misunderstanding. What would reduce vibration more than a snug fit between the tube and the separator?

The gap between the tube and separator.

The gap between the tube and the separator is pretty big, varying between 1″ and 2″ inches.

In terms of performance, the K&N air intake kit worked as advertised. In addition to measuring horsepower, we also measured fuel economy. Our test vehicle, a 2007 Tundra with a few thousand miles, enjoyed about a 1 mpg average fuel economy improvement. Our test truck averaged about 14.5 mpg before the intake was installed, so figure the K&N intake improved fuel economy by about 7%. If gas costs $4 a gallon, it will only take about 20k miles for this kit to pay for itself, not counting the filter cleaning kit (needed every 50k miles or so). When you factor in the lifetime air filter, buying a K&N 63 series air intake kit makes financial sense.

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Sound of the K&N Series 63 air intake kit installed on a 2007 Toyota Tundra 5.7L V8.

Like all the air intake kits we’ve tested before, the 63 series looks and sounds better than the factory air box. The chrome surrounding the big air filter makes this thing look impressive, and the engine breathes loud and clear. In fact, the K&N 63 series sounds the best of any kit we’ve heard. It’s probably because the K&N filter isn’t encased in a sound-absorbing plastic box. It sounds good, and perhaps that’s why K&N decided to make install a little more complicated.

Performance is good too – just about the same as every other kit we’ve tested. Our data showed a 10 hp increase at about 4300 RPM. That doesn’t match K&N’s official dyno tests, but it’s still a very decent power gain. Throttle response was also noticeably quicker once the K&N 63 series was installed.

Our tests show that the K&N kit performs as well as any other kit we’ve tested. While this K&N kit review was the first time we measured fuel economy, it’s a safe bet that the Volant and aFe kits we’ve tested (see our aFe intake review and Volant intake review) also improved gas mileage. In fact, they’re all probably equally beneficial when it comes to gas mileage based on the fact that all the horsepower numbers are so similar.

Bottom Line: K&N’s kit sounds great and performs well, and we documented a solid gain in performance AND fuel economy after installing the kit. Unfortunately, installation is the problem with the K&N 63 series. The install process is tedious (compared to other air intake installs) and it’s more complicated than necessary. Complication increases the chance for errors, as witnessed by the filter falling off the test truck. We also can’t help but we feel that the K&N kit should be less expensive than its competitors considering so much of the assembly is done by the end user.

We recommend the aFe air intake kit over the K&N 63 series air intake. Performance is similar, but aFe’s kit is much easier to install and there is less that can go wrong.

Filed Under: TundraHeadquarters.com

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  1. Perry Petek says:

    I’d like to see a review of the TRD air intake kit. Looks to be nice quality from the photos I’ve seen. And the meter to clean the filter is cool too.

  2. Mickey says:

    I’m glad I got an AFE with no filter replacement and no oil.

  3. Mickey says:

    Forgot to mention mpg’s I got for 60mph – 22.3mpg, 55mph – 24.5mpg, 80mph – 17.3mpg.

  4. Kip says:

    Im no stranger to wrenching, so I can gaurantee that I installed the 63 series right on my 08 Tundra 5.7, but after installing I heard a sharp whistle @ about 2K RPM’s. I realize that this filter is sucking mass quantities of air, but the whistling noise can be annoying on the freeway. Has anyone else noticed this? By the way, wrapping some foam tape around the plastic tubing where it penatrates the heat sheild really helps, and doesnt look bad too.

  5. Mickey says:

    Kip AFE doesn’t whistle.

  6. Steven Hitchcock says:

    I agree with Perry Petek, I’d like to see a review on the TRD CAI for the 5.7’s.
    I’ve been looking at getting one, and would like to see the specs on a test that you guys here at THQ run.

  7. Perry – It’s on our list. The trouble is that we can’t get a free kit from TRD like we can from everybody else. I’ll work on it and see what I can do.

  8. Alan says:

    Great write-up. I’ll put the K&N on my list of things to don’t.

  9. Alan – Thanks a lot. K&N was great to deal with, and we really appreciate all their help. We still think their performance air filter is top notch and highly recommend it.

  10. keith says:

    Is there any way to get rid of the loud whistle noise???? Its driving me crazy!!!

  11. Keith – There’s a chance that you’re hearing a loud noise because one of the pipe-clamps is loose. You might want to double check them all and make sure they’re good and tight.

  12. John Francoeur says:

    aFe looks like the class of the field…thanks for the informative testing and results reviews.

  13. Jason says:

    John – For sure.

  14. Dan says:


    Thanks for your effort on this.

    I have K&N filters on both of my Harley’s and have really enjoyed them.

    Just last week I traded in my 2007 Tundra Double cab for a 2010 Crew Max Limited and I decided to add a cold air intake.

    I have had a tough week in trying to determine the best to buy. I’m very new at this sort of stuff. On this, money is not an object. I ordered a 63 K&N this morning, but not for the price…. then I discovered your review!

    Now I get the impression that the K&N 63 is a piece of crap. I would buy a TRD Super Charger, exhaust and intake, but my wife would kill me and if she didn’t, I’d be eating dog food for the rest of my life.

    A Toyota tech told me that the aFe is a piece of junk. I wanted a slight bit more sound than what I have seen the TRD to have, so I decided on ordering the K&N…. until now.

    Well, I guess I will cancel the order and either start over again or give up the intake upgrade altogether.


  15. Jason says:

    Dan – I don’t think it’s a piece of junk, but it’s not my first choice. Not sure why a tech would tell you aFe’s kit is junk – the quality of the kit was second to none, the filters are excellent, and the performance numbers were comparable. Did you see our review? http://www.tundraheadquarters......ir-intake/

  16. Dan says:

    Jason — Thank you for your response. I didn’t mean to indicate that you said it was junk, rather, that based on what I am learning, it looks like junk to me.

    I should have pressed the tech for details regarding his position on aFe’s. … I will.

    This is what I think that I will do now.

    The K&N should be here by Friday. It was too late for me to cancel the order. I will install it and try it out, but if it so much as looks at me wrong, I pull it from my truck, send it back and order then an aFe.

    Here is what is important to me: Performance, sound and overall quality. I couldn’t care less of the cost. If it’s tough to instal, oh well, I’m retired, so time is no big deal… perfection is.

    As for sound… I want a system that sounds stock or near stock at idle and cruising down the freeway, BUT, when I stomp on it, I would enjoy hearing that motor coming alive. I don’t require loud pipes, just a strong sounding motor with a bit more hp and throttle response.

    I am not certain from the videos I’ve heard on the internet (I live in the sticks, so I can’t hear it in real life), but I am getting the impression that K&N may be a bit loud for me– while simply cruising. My Harley’s just rumble along, they’re not obnoxious, yet when I hit the throttle hard—even the angels get out of my way. ;>)

    Thanks for all that you do….

  17. Jason says:

    Dan – Thanks for the thanks! 🙂 I think the Volant is the loudest kit – K&N’s kit is “average.” Not really obvious at normal throttles, but very fun when you stomp on it.
    If you take the time to really “build” K&N’s kit carefully – and it’s like building a model or something – you’ll have success. The other thing to do with the K&N kit is to get under the hood a few times during the first month to make sure all the clamps are still tight. The trouble with this kit is that the filter falls off quite a bit on new installs. It’s either because it wasn’t tight enough (install error) or it somehow worked itself loose (being new parts and all). Either way, I think it’s a bad way to design a kit. Why make the end user do so much assembly? Seems cheap.
    Still, lots of guys have em’ and love em’, and I’m a big fan of their filters, so the K&N kit is definitely not a bad choice…just not my favorite.

  18. Dan says:

    Jason — You are being very helpful.

    With regard to the clamp screws coming loose, I wonder if a very small bit of blue Loctite would remedy that or might it be overkill?

    I’m going to try this thing just to see if I like it. K&N told me that if I hated it, even after using it, they would refund my money.

    UPS tracking has it arriving tomorrow, so I should get some miles on it this weekend… If it doesn’t knock my socks off, I’ll order an aFe on Monday.

    Here is the insanity of all of this. It took me about an hour to decide to buy a $46K truck, yet I have been fretting for over a week on what air filter to buy. LOL


  19. Jason says:

    Dan – For sure. The loctite is a good idea – I think it might help to clean the clamping surface too before install (it’s a very slick rubber coating). Let me know how it goes!

  20. Dan says:

    Jason — Will do. It’s in town now, so I should see it within a couple of hours.

    My son thinks he want’s this instead of his TRD, so if I don’t like it, I might make it his birthday present for the next 10 years. ;>)

  21. Jason says:

    Dan – You’re too nice man – that’s a tremendous present! My old man would have given me the old airbox and told me to buy the rest of the car! 🙂

  22. Dan says:

    Jason — Last night my son invited me to his house for installation. All I did was stand around. He was finished with the instal in less than an hour.


    I thought it sounded nice while parked, but nothing to really speak of.


    We quietly made our way through the city streets. It all seemed very stock to me… with a wee bit of base.


    Then we got on the highway and at about 20 MPH, I hit the throttle. OMG did she come alive!!! She has power, she has soul, she has an attitude and she shouts all of this to all that can hear…. kinda like me. LOL


    I was pleased that while cruising the sound was almost stock, when she’s opened up, it’s dancing like with the wind in a thunder storm. It can quickly change your mood.


    I was quite impressed with the changes in this truck considering that this was only a simple intake modification.


    Of course, it’s like anything, now I want even more. It’s an addiction. LOL I’m 61 years old so I should know better… ;>)


    We spent about an hour trying to waste as much gas as I could. It was all good.


    I got home about 9:30 last night and was met by my wife, already dressed in her robe. She jumped into the truck and said, “show me”. I cruised around quietly for about 5 minutes, then I hit it and brought her up to 80. My bride loved it and suggested that I likely felt 19 again. By that comment, I’m not sure what all she expects LOL, but it’s very clear that she likes the new heart this truck now has. Hmmm maybe I can get her to buy me a Super Charger. ;>)


    My plan is to drive it for a week and then evaluate how I feel about it. We will make a 300 or 400 mile trip this weekend just to get used to it. I will have to check the gas mileage at some other time, as I am having way too much fun with the throttle right now. ;>)


    I may keep this K&N, but if I don’t, I will buy an aFe… it looks very clean. One thing is certain…I will never own another truck without a performance intake system, period.


    There you go… a happy ending.


    ~Life is good~


  23. Jason says:

    Dan – Very cool. Sounds like a good day. Thanks for sharing…don’t forget to check the clamps for tightness!

  24. titan4486 says:

    So on the main review page the K&N 77 series is mentioned for the 5.7. Has there been any review of that one? Is it safe to say it will have the same problems as the 63 series?

  25. Jason says:

    titan4486 – The 63 and the 77 are the same intake – the only difference is the chrome/polished parts.

  26. Chad2311 says:

    Just bought a 2011 Tundra Double Cab 4×4, 5.7ltr, with the TRD off road package. My isssue is do I wait a couple of months to get accesories or just order 2010 parts because they are the same???? Help?

  27. Jason (Admin) says:

    Chad2311 – Same truck in nearly all respects. Thinks like air intakes will work just fine even if they say “2010.” However, just to be sure, it’s a good idea to call the company that makes the part and ask for verification.

  28. Huntmachine says:

    A buddy showed me his K&N 63 intake on his 2007 Tundra and I was impressed (nice sound). Just bought it myself off of amazon.com for $229. Bargain price for an awesome intake.

    Side note: bought the K&N replacement filter (stock air box) 2 years ago and it whistled like a sumbi#$@ without any mpg or desirable sound benefit. Threw it in the trash.

  29. Jason (Admin) says:

    Huntmachine – That is a great price.

    When we tested the K&N filter we found it improved gas mileage, but every truck is different. Hopefully your truck responds well to the full kit.

  30. Huntmachine says:

    The K&N intake also whistles. There is a spot just above flat ground cruising speed when it does so. More gas and it sounds awesome with no whistle. Give it a small amount of gas to maintain criusing speed and it doesn’t whistle but if you need just a little bit more like climbing a slight grade and it whistles. Kind of annoying.

    Much better throttle response thought and 1 mpg better. I can live with the whistle since my Tundra is a toy. If I had to commute in it every day I’m not sure if I would since it is a monster bone stock.

    Anybody have any info on what might be causing the whistle? All fittings are tight. BTW my buddy told me he has the same whistle. I suspect the throttle body butterfly crfeates it at that “sweet spot” just above cruise speed.

  31. Jason (Admin) says:

    Huntmachine – If you hear a lot of whistling, be sure to check all the pipe clamps and fit on all connections. That was a problem we noted right before the filter fell off.

  32. loonzter says:

    Would a 2011 4.6 benefit from this upgrade or does it only come for the 5.7 engine?

  33. Jason (Admin) says:

    loonzter – I believe that K&N offers a kit for the new 4.6L, and because almost all new engines have that air intake silencer (and cheap paper filters), they can benefit from an air intake system. How much? Not a lot, but some. As I’ve said in other reviews, half the reason to buy this part is because it makes your truck engine sound a heck of a lot nicer…but that’s not a “logical” reason to buy, so I understand when some people chose not to get one.

  34. Leo22 says:

    Which is considerably louder K&N or the AFE?

  35. Jason (Admin) says:

    Leo22 – The Volant is loudest, but the K&N and aFe kits are about the same.

  36. Ryan says:

    I recently installed the K&N and I also have the whistling issue. I really don’t think that this is a “tightening” problem as I have made sure to check literally every time I take it out of the garage. I even had a local shop look at it to make sure I wasn’t doing something wrong. I think this filter just causes a whistle sound for some reason.

  37. Huntmachine says:


    There is no problem to find. The K&N whistles at certain speeds and RPM’s. Mine does it and so does my buddies’. Nothing to be done other than to consider it your supercharger. Good thing it increased my MPG and throttle response or I would be pissed. Sounds awesome when you mash the throttle too.

  38. Ryan says:

    Thanks for the confirmation. I was just worried that I messed something up installing it. It does sound pretty good though, you’re right. All and all, I am still happy with my decision.

  39. Charlie says:

    I just bought an 04 Tundra with this intake kit on it and this is my first cold air intake. I just got the truck so how often should I oil and change the filter? And is that all I need to do. Thanks

  40. Huntmachine says:

    Pretty much never unless you are running the Baja 1000 on a regular basis.

  41. Charlie says:

    Yeah true. The intake I think is a few years old and I live in the desert and am constantly kicking up dirt to the point where my engine is covered in dust. Still think there’s no need for oil or at least a new filter?

  42. Aybee12 says:

    i got a 02 4.7L, which would be best?

    • Jason (Admin) says:

      aybee12 – You don’t have a lot of options on the 4.7 – I think K&N might be the only option, in fact.

  43. Anonymous says:

    on my 07 tundra 4.7 i got the K&N cai.back in 2009. no whistle, no filter falling off. run it in Utah, down to Texas and back. no problem. a year later add a MBRP exhaust. the next year headers. got some great sound inside and out. turn heads. i did check the clamps this year and they need tighten but no whistle, the filter stay on. one clamp was bad took it off. use the stock intake clamps. i not going to worry about it coming loose it’s from toyota they don’t tell you to retighten the clamps so they should stay tight. mph it gets about 1 or 2 more.

  44. Caleb says:

    I have a 2005 Toyota Tundra 4.7L V8 SR5 TRD Off-Road Edition, i have dual exhaust and some nice sounding Flowmaster tips, for Xmas i plan on buying a CherryBomb Extreme muffler, hollowing out my 2 catalytic converters, a K&N Air filter and a K&N cold air intake. of course by reading this you know i love making my truck loud as possible LOL so if i get a K&N air intake, which one is the best for me to buy? which air intake will improve MPG, performance and most definitaly the sound??

  45. Jim says:

    Just installed a “77” kit on my 2010 5.7 Tundra with about 25,000 miles used to tow a 7700# fifth wheel. Also have a Borla exhaust system. Between the two it is loud when pushed. It appears to be stronger but no data. It did initially bump the idle up; not sure why. Has anyone had any warranty problems with Toyota with it installed?

  46. Jman says:

    I got a 2008 tundra 5.7L V8. I bought the intake a couple weeks ago despite the review on some little problems. Held off on puttin it on because had mustard colored gunk on the engine cap. Went away with the warm weather, so it was time to put on the intake. The installation was a little time consuming, but I enjoy projects like this so this wasnt a bother. Took two hours install, takin my time. Biggest difference I notice is the sound. When accelerating to the interstate, sounds like a hot rod. I notice a whistling, but I dont mind it although it is very noticeable. Throttle was already sensitive enough so didnt see improvement. Average MPG went up. I floor it all the time, and i still see around 18.5. Great intake if you like K&N. only problem is the gap between the tube and the shield. wish they would include something to put there, but i already stuck something in there myself. Works great. Reccomend it to everyone that likes to take care of their truck

  47. Mike says:

    For models 12-13 they made a new Easy-to-Install K&N 63 Series Aircharger Kit that took me a 1/2 hour to install & it was my first time installing an intake. Sound is good, especially when u control the throttle around 3k rpm & the HUGE throaty noise that comes off is so amazing. But the normal whistle complaint at 1500-2000 rpm would still be mine… haha

    My dad has an aFe in his truck & I like the sound of it too, but it can’t beat that intake note at 3k from the K&N

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