iv got a k/n. had it on there about 10monthes. didnt notice any change. i have the oem pre filter on it. iv washed it and oiled it once so far. way cheaper than buying a new filter each time.i paid $35 total inclued s/h plus $11 for the recharge kit. think i can get alota uses outa the rechage kit. i say aslong as the prefilter is on and its cleaned and reoild i cant see why it wont work.....

 

Well, I only paid $35.00 for the K&N. And I'm not sure even a 850cc engine is coming close to the airflow max for the size of the filter. The air filter on the 2.4 liter engine in my wife's old Nissan Altima was smaller than the air filters on Sportsmans. And yes I understand the driving conditions are much different on OHV's compared to street vehicles. I didn't run the prefilter at first, but had a change of heart after a dusty ride, and thought what the heck, it can't hurt.