Review on K&N Engine Air Filter: High Performance, Washable, Replacement for 2009-2017 BMW (520i, 528i, Z4 sDrive 18i, Z4, Z4 sDrive 20i, Z4 sDrive 28i, 528i xDrive, X1, X1 20i) - Model 33-2963 by Jeremy Kakaruk

I bought this filter for my 2014 X1 xDrive28i hoping that with a looser filter I would hear a little more turbo induction noise. To my disappointment, the turbo sound hardly increased. I can get it to make turbo sucking noise under the right circumstances, but for most daily rides I haven't noticed a difference. mostly correct. After installing the filter, I did not notice any increase in power / acceleration, as well as an increase in fuel consumption. If there have been improvements over the stock, they are so insignificant that I don't even notice them. The reason I gave this filter 4 stars is because: 1) Overall the filter fits great, comes pre-lubricated with oil and is made by a reputable company. , and 2) it can be reused, reducing cost and waste with standard paper filters that must be discarded after each service. Overall, it's just a more expensive but reusable air filter. It does the same as the standard device but is three times more expensive. But I think cost is a moot point since you don't have to replace it. There are many negative reviews about these types of filters and whether they add more "dirt" to the engine because they flow more freely, but I disagree with those claims. If you follow the manufacturer's recommendations for keeping this filter clean and properly lubricated, it should filter the air entering your engine well.