I fabbed one. It was a very simple and easy fab job. If you look in the exhaust section I made a thread about it with a couple pictures. I have gotten nothing but compliments on the sound. Fair warning: it is very hard to keep from wanting to get into the second cam all the time.I am looking to do this also. Did you fabricate a pipe to exit out of the diffuser or does one exist on the market?
I will try taking a video with my phone and camera and see if the sound comes through at all.