Well first of all I would close off the two foward facing holes on item #18 with a dence fome material like hood insullation. This will prevent drive belt material (on the left side) and brake dust (on the right side) from entering the air box. To determin if your airbox is the right size install a fitting on the front of the airbox between the carbs and hook a vacuum gauge to that fitting. If the gauge shows any vacuum reading then you should think about gutting the airbox.
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