Because K&N moved manufacturing to China where someone "optimized" the design creating many failures.
As they should, before someone got hurt or killed over a crap oil filter.
The point is whoever makes oil filters for K&N is making them for another brand.
Regardless, the safe track thing to do is ban any filter with the spot welded "nut". They don't know which filter may have a failuulre at that point, or how the filter was installed and the nut possibly over stressed. People's safety is more important. Use the hose clamp and safety wire trick.
Do you realize K&N's nut failures occurred 10 years ago?
If tracks don't allow them anymore, then they don't have track failure data of said filters with a spot welded "nut". The bottom line there was a reason they were banned, regardless of what they may be now.
Yes, if tracks have banned the nut then they don't have record of failures on the track. They never did have on-track failures, all were street "puddle under the bike in the garage after an oil change." And ancient history.
