K&N Cold Air Intake Kit: High Performance, Guaranteed To Increase Horsepower: 50-State Legal: Fits 2005-2014 Nissan (Frontier, Xterra, Pathfinder) 4.0L V6,57-6014

This is a well-engineered bit of kit, I especially like the design of the heat shield with its cushioned seal. I was a bit concerned after seeing another review claiming rattles given that non-OEM can propagate poor results. I was also concerned about fitment as the Amazon Garage claimed it wouldn't work on my 2009 CrewCab , short bed, 4x4, 4.0L Frontier. Took a chance as the 4.0 Xterra/Frontiers are nearly identical mechanically over their respective model years. I took my time installing, utilized all the sealing material, trimmed to fit perfectly and double checked my work...net result, zero rattles, perfect fit (almost, see below), and per my butt dyno, the claimed power gain is at least close which is unusual for a CAI, usually the cool sticker is about as effective. It seems some real thought and engineering went into this, it also tells me the stock setup was fairly restrictive. As another reviewer pointed out, the plastic tube reduces the chance for heat soak, and the heat shield is effective. I hemmed and hawed at dropping the $$'s on a CAI, but it turns out you get what you pay for, this time in a good way. As for sound, it's stock quiet at idle, a little louder (in a good way) in normal driving conditions, and obnoxious at WOT. At WOT I like it, my GF hates it, 'nuff said. The fitment caveat, kit comes with a replacement crankcase ventilation hose to replace the stock piece, it is about 6" too short, and half the diameter so you will be buying that elsewhere. Maybe why Amazon claims the kit doesn't work?? Otherwise, it's a perfect fit, but you'll need the 5/8's hose. Overall, very happy

The product box arrived in pretty rough shape, however the contents appeared to be okay. However there is one issue, the sealed parts bag that was provided appears to have supplied the wrong hardware type, included should've been 6 M6 sized bolts that correspond with the provided nylon lock nuts. The bolts provided are definitely too small. Email sent to KN customer support.

Fantastic intake kit. Took me about an hour start to finish to install and the end results look and perform well. The truck has a much more noticeable growl than it did before above 3000rpm. It isn't LOUD by any means, but it does sound better. Sounds more like my custom G35 now. I don't have access to a dyno so I can't say anything with regards to increased power or fuel efficiency but I CAN say that cruising at 65mph on the freeway the truck was 300-400rpm less than it usually is. Good sign. Overall a great kit, well thought out, and should be relatively bullet proof. The ONLY thing I would change would be to add additional silicone bumpers around the opening in the side of the enclosure that the intake tube goes through. Not a big deal and I'll likely pick up some silicone weather stripping from the local home store to fill that space up a bit more. One other little quibble. One of the hose clamps simply wouldn't fit where it was supposed to go. I went through all of the provided clamps only to have to remove them for use other places. In the end I had to salvage a clamp from the old intake to reuse. I do want to leave a comment for anyone thinking of getting this or any cold air intake kit. There are people that will scoff at these indicating that it isn't possible to gain any efficiency or performance simply by installing one of these. Aside from the well documented proof that cooler air is more dense and therefore capable of providing more power, having a breather element and tube that reduces restriction DOES help. No, it doesn't 'add' horsepower but it does reduce the amount of effort the engine has to use (taking away horsepower) to inhale. Case in point - grab a plastic coffee stirrer and a soda straw. Put the stirrer in your mouth and breathe ONLY through the stirrer. Run around the block. No do the same thing with the soda straw. THAT is what these provide. Don't expect miracles. Don't expect to double your horsepower. DO expect the engine to run a little more efficiently which does give measurable gains in mileage and horsepower.

I’ve had this intake on my Xterra now for two years, and after fixing it, decided I’d write a review. I will say it sounds great at higher rpms and the cleanable filter is nice. As for gas mileage or extra power, I haven’t really noticed much, maybe a little after 4K. The reason for two stars is that the thing rattled like crazy. Any pothole or bump in the road and the filter rattles up and down making contact with the air box and fender. The mount where the intake tube goes through the air box does not hold it sufficiently. It’s designed to allow it to take some vibration from the engine, but just doesn’t work, flat out. Finally, after getting a plastic printer, I designed and mounted a part to hold it properly. Overall, I’m fairly disappointed as I’ve always had confidence in K&N.

Thoroughly impressed with this product on my 2011 Nissan Pathfinder (4.0L V6). The install was as simple as it could've been, and it seemed vehicle specific and the fit and pre-drilled holes were relatively accurate, which was great. The throttle response improved. The sound difference is subtle below 3500rpm, and sounds great in the higher rev range. So far, I've seen about a one mpg improvement with almost 100% city driving, and with me driving much less conservatively because it sounds so nice. Thanks K&N!