Originally Posted by Killer

Before we stamp any black and white opinions down lets backup a bit and evaluate all scenarios first. If you ride around on a modded motor, you WILL see a performance benefit from a free flowing filter like the K&N, theres no rocket science there. You dont see race engines running around on stock airboxes do you? So its always a question of what do you need for and out of your motor and then you weigh the pro's and cons. I ride around town on a very wickedly fast Apache that will take most rd350's in the city (forget indian bikes) and i run a K&N...it plays a role in my setup and adds to performance. I dont ride around in or around muck nor do i do long rides, i see very little mileage but most of it is fast paced. My engine will see a full overhaul long before any detrimental effects of a free flow filter set in and even that will take a couple of years...so this filter suits my needs. Why the explanation? to illustrate that there is an application for lots of things, including filters like the K&N. Does it make sense in my opinion to slap on a K&N on a stock motor?
No.