A few holes about one inch in a pattern close to the back area of inner air box will give plenty of air. As long as you don't change the outer airbox cover i have seen a lot of cool ways to fix the need for more air, still needs to be functionable for all types of weather. Carefull w/ holes in the front, is filter K&N or paper element? Too much air will make these bikes run too lean for street use. The Velocity Stack is tall so noise is sometimes an issue. If worried about rain ect. Drill a 3/16 hole in the back bottom area its slanted, so good luck w/ those mods.