Being a young adult in the 90s K&N was all the rage. Since I have a brain though, I figured out for the most part K&N is, IMO, basically a sham company offering scam products. Products like the K&N "Stub Stack", any one remember those? ****ing con artists BS tantamount to today's fuel economy gadgets. Maybe their oil filters are good, or still good, I dunno, IMO there's planty of other options that perform as well that cost less.
K&N air filters for people that like rebuilding engines a lot. As other's have said, verified over dozens of power test they do nothing except let far more junk into your engine.
If you're looking to gain power from an air filter, instead lose 5 lbs because you'll gain a greater benefit from that over any gains from an air filter. If you have no other options to lose 5 lbs, or maybe maybe start looking at your air filter.