Thats a bit strange, I have 6 or so holes, a big one at the entrance then a few small ones then a big one again before the bend then 2 after....
Anyway I have taken a slightly different approach to the problem...I got a tube from b&q but I wasnt happy putting a pipe in which had quite big ridges and wasnt that snug a fit so I decided to block the holes in the most minimalistic fashion. I got a sheet of platic laminate and cut a rectangle to stick to the roof of the air box covering the holes. i also put a small strip over my holes after the bend. Works a treat!