I'm kinda new to atv mechanics, but have some basic knowledge. I bought a used 400ex with 12:1 wiseco piston 100 over, carb has been rejetted. When I bought it, it had no airbox lid, no type of filter on it and no snorkel. I have been researching on ebay and there are K&N powerlids and then the normal K&N filters, and also prefilters. I don't do any driving through deep waters. I'm just cursious which combination of filters everyone would suggest. I'm sure it needs to breathe easy, but I still want to protect it. Any educated suggestions would be appreciated as I'm trying to learn. Thanks!!! - Shawn

 

also, this has a 440 kit

 

Personally, I am a foam filter fan. I like White Brothers most. I use an EHS airbox lid.