Here is one of the better test examples:
https://www.project200.com.au/dm-iso5011/As you can see, the K&N is much, much worse than most anything else at filtration. When it is brand new, the K&N does flow better, but it rapidly degrades with use.
For intermittent race use where you are exposing it to minimal overall use, the K&N is probably ok. For something on the street where you are putting on a lot of miles/runtime, I would not recommend it.
