A little bit of heat from a heat gun,some WD to make it slide.Put a hose clamp on it and call it a day.The rubber will stretch.Another clamp on the air box tube and your done.I would also get rid of the top of the air box and put a nylon over the oiled air filter.The more air the better just jet up.The big hole in the bottom is for access to change the jets,there should be a hex screw in plug there.