Hi Dave, I'm running the standard air filter, I was considering the K&N, but it was $207.00 nzd vs $120.00 for the Honda one.
At the same time, I changed to semi synth and balanced the carbie's as well, so I can't give all of the improvment to just lifting the needles, but I'm sure (seat of the pants) I've got more mid range.
He who dies with the most toys "wins"
Ross, keep 2 things in mind regarding the air filter;..
#1,..the K&N will last forever, due to they can be cleaned and reoiled.
#2,..if you put the K&N in, your bike will run a tad leaner, due to more air flow.