K&N Air Filters

[SeCX-9]

Hi,

Anyone here install a K&N Airfilter on your CX-9?

I have a 2008 Mazda CX-9 AWD GT with 3.7L Engine. K&N Filter 33-2395 per their recommendation.

I have been using a ScanGauge II for the last 4 months and during my 25 minute commute have registered about 22.7 to 23.1 MPG using factory paper filter. All highway.

Installed the K&N filter 3 days ago and now getting 20.5 to 21.0 MPG doing the same commute under pretty much the same conditions.

Decrease. NOT what I expected at all.

So I email their support team.
I asked about a break-in period and they said none is required.
They indicate (via email from Paul at K&N) that their is no guarantee with MPG improvement since their are so many variables. He only claims improvement in Horsepower in his first email (and 100% satisfaction gurantee or money back)

Then I asked, how can I show the improvement in HP using my ScanGuage][ and he replies "A replacement air filter typically gains between 1-4 whp, but there is no guarantee for a horsepower increase with a replacement air filter."

So in reality, there is no guarantee of any improvement other than not having to throw away my airfilter which I paid $50 + $10 for the cleaning kit and $9 shipping. That's about 4.5 air filters at $15 a pop.

Has anyone tried the K&N filter and noticed any MPG or performance improvement? If you did, please tell me how.

Thanks

[squidly]

I have one and didn't notice a change in MPG at all.
In fact, I've had K&N filters in 4 of my last cars and never noticed a
change in MPG. Performance a little bit, but not MPG.

[CX9 SportOwner]

I put one on mainly so I don't have to change the filter all the time, and get better flow as it gets dirty. We do get a little more low end, which is typical of using a K&N, but don't think we get better MPG.

[l-miwa]

I've had K&N filters on a number of vehicles, including our CX9, and have never noticed an improvement in MPG or horsepower. While I admit that I didn't put it on a dyno to see if it gained 1-4HP, a 1HP difference on a 250HP vehicle is a 0.4% increase - about as insignificant as you can get!

I purchase them because they never have to be replaced and more than pay for themselves as we tend to keep our vehicles for a long time (>200K miles).

[Scott P]

The only thing you might notice is a slightly higher silicon content if you do an oil analysis. Many people have experienced a decreased amount of filtration versus a stock paper filter.

[ceric]

I have K&N on for about 7000 miles now.
What you get is "response" of engine thru better breathing.
MPG? Not noticeable. K&N does not claim that on their website either.