Everybody drills holes in their side panels to made their bikes run better, but it's a bit more complicated than that, the idea is to take away the negative pressure in the air box, if you make the holes to big it will have flat mid range and top end. If the holes are to small it will restrict bottom, mid and top end. This is where our Air Induction Kits comes in. The Americans have used these kits for years and if you look at any picture you'll see a very similar design, it lets the right amount of air into the air box and should match perfectly to any after market pipe or HRC tail piece. Also looks very trick and tidy.