is a k and n filter worth buying, any noticeable difference ?

[Grahamm]

So how on earth can you comment on them?

Because I have seen threads like this one before many a time, here and in other places.

If you want to spend the extra money, feel free, but, like upgrading my rear shock from OEM to YSS instead of Nitron or Hagon etc, for the majority of riders, the difference will probably not be noticeable or beneficial.