The XB9 exhaust did not have the valve and associated hardware...
I'm gathering up all the stock muffler parts because I find the Jardine on my new-to-me Buell XB12S is too loud as well. Someone told me about a quiet kit for the Jardine which is basically a plug that reduces the outlet diameter. They are $50 on Amazon so I'm going to give that a try. I'll post my opinion of it here after I've tried it.