K&N for the economy, (a one time purchase), the additional power and 50 years of great performance from K&N for me. My BMW had over 300K when I donated it to a charity still running fine and a daily driver. Never any problem with burning oil nor oil on MAF's like those who seem to think more oil is better. I have never had a problem with dirty oil from so called poor filtering. Unlike paper filters performance does not drop off as rapidly when dirty, 3 years driving the AZ desert is torture on any air filter but the the drop in performance and economy was noticeable after about 4000 miles on a paper filter. After installing a K&N I went about 10000 between cleanings and increased MPG by 2 miles. My gas mileage went up almost 10% (3.2 avg. hwy) with the MP215 kit and I attribute lots of that to the K&N air filter and CAI on the Mountune air box. as it alone has improved mileage in most of my other cars. Over the years I have read the competitors statements about the filtering but with all the silicone intakes I have used and silicones affinity for dust clinging to it I have never noticed any in the intake tracts. Another old wives tale as my BMW proves the cylinders never saw a lot of dust and dirt in the intake tract. So we all have opinions....that is mine, my many years with K&N has been a positive put some money in your pockets experience for me. I also do not think Ford would use it and warrant the cars engine if they saw any problems with it as they sell it through Ford Performance. It would be stock on all of the performance cars if it did not require maintenance I am sure. And that alone is a consideration for owners, are they actually going to maintain it? With the number of people raising hell about having to check fluids on this Forum I would think that would be a big deal to some. It does take time to clean and re-oil.