I have a drop in K&N panel filter in my stock air box. A few weeks ago I removed the rubber boot that connects the side of the air box with the fender of the truck. Has anyone else done this? Should I leave it off or put it back on????

 

Put the boot back on and cut a hole in the bottom of your air box. I also ran a hose to my box from bellow the font bumper that way it gets more air but its cold air only.