I agree with Dez. I have run K&N filters on everything and have never had a problem with infiltration.

My last check was the wife's Wolverine 450. We got it in 2006, I tossed the stock filter and drill holes in the airbox lid. In 2011 I rebuilt it when a valve was starting to leak. The cylinder and piston looked brand new! This quad sees alot of Michigan sandy trails and dust.

Just my 2 cents.