Rock roads and trails through woods. I guess during summertime I would get a little dusty going down gravel roads. Right now I have a foam one drenched in a heavy oil. Lol I need to replace it anyways but now I know to get foam instead. One question though, wouldn't it run better off a k&n as long as it got jetted to it? Mind you I don't have much mechanical experience so some of my questions may seem dumb, but I'm learning still. Lol