I used K&N very long time back on my old Mitsubishi, and now I just Simota/Works on all my cars (Toyota, Suzuki, & Nissan). Honestly no issues whatsoever, and you should not expect too much added power for just using such drop-in filters anyway. So in general I think the Simota is the best value for money. Anyway the material and design also basically copies K&N.

If you really want a good filter actually its not K&N also but APEXi dry cloth type filter but nowadays this product not available anymore. K&N/Simota give about similar filtration capability (plus/minus ya) but the main weakness is the oil which can affect AFS. The APEXi though is not using oil so it's cleaner like original filter yet it flows more air, believe it or not! Very long time ago there was a comparison test done on a GTR R32 between all these after market filter types and the winner was the APEXi as it gave the most power gain yet also provides equally clean filtration like std filter! K&N came 2nd with similar power gain yet got that oil trace getting sucked into, so not as clean. Then 3rd came the HKS foam filter which was very poor filtration and actually not as much gain as the first 2 also. Last was the Blitz metal mesh filter which gave about similar gain to HKS but practically did not filter anything hence very dirty! So for me I avoid any foam and metal mesh filters, no matter what brands!