Im afraid there is no real way to remove the "Db killer" in the stock exhaust. Here is a thread from the MT07/FZ07 forum
http://www.fz07oc.com/threads/is-it-possible-to-remove-the-db-killer-from-the-stock-exhaust.254/
Also here's a photo of a stock exhaust breadbox cut in half so you can see for yourself.