A filter is a filter basically. To gain from either one, you have to adjust the fuel mixture to the amount of air the filter is able to breath. Well duh, we all know this. K&N's are good filters and i like them and clean new will definitly outperform a stock filter, couple horse or so. However, like i say, this will benefit you the most when racing, cause you're gonna clean your filter for every race day so it's gonna be more consistent. For just everyday riding etc... it's not going to be worth all the effort, and that's why i'm saying a stock filter will suit you just fine.
Catch my drift? Just my .02
I KILL GROUNDHOGS! Remember that today furry friend!