+1 to skapan
I personally run K&N on everything I have ever owned. simply bc with air filters I like being able to clean and reuse them instead of continually buying new ones. If you clean and oil them properly I havn't seen any actual proof of people having problems with them. Otherwise my car and jeep both see better gas mileage than they did before. the car did gain a good bit of go from the K&N cold air set up.
As for the filter on the bike, I havn't noticed any power gains/losses since I replaced the stock filter at the 6000mile service. the sticker looks pretty good on the side of the bike though. haha