just replaced the old paper cone filter with a k&n filter. it sounds awesome with the lid off the air box. however you still get the little wine noise at idle. with the lid back on i can't say i have noticed any difference in performance. it makes a slightly deeper noise with the lid on. i did a little test. i took both filters off and blew through the standard one and the k&n. the standard one does have more resistance than the k&n. however the standard filter was bloody grubby and left me with a dirty fake tash!
the k&n seems well made and looks a lot better than the standard filter. not sure if honda would tear up my warranty on the next service if i left the k&n on so i have kept the old filter. for my next visit.

 

I've had no problems with Honda & my K&N filter. You're "supposed" to tell your insurance company though - barstewards.

 

I fitted one last night and my impressions were not much difference at first. Coming back from footy today though and foot flat on the pedal at a ton it got to 130 a lot quicker and made a lot better sound . Well it had to be done cant let these TT boys think they own the road !!!!

 

How long did it take you to realise?

 

luckily my girlfriend pointed it out. however i did have a conversation with my next door neighbour! bastard didn't say anything!