I think the issue would be, where do you actually put the cutout? I've looked into it before, but its very difficult/impossible to fit cutouts in such a tight area between the header and cat converter. JD's setup is very custom, don't forget that. Also, forget retaining the flex pipe. There is not a lot of room to work with and you would have to mount it downstream from the primary 02s. Unless you have your own equipment (welder, etc) I see this as being a pretty costly project for someone to fabricate for you.
Edit:
I just looked at the link. What's the point of simply bypassing the rear section like that. Cost of fabrication and parts would be getting close to a Snake Oyl rear system, and I doubt it sounds very good. Plus there would be almost no HP gain. Dumping before the Cats would be the ideal solution, but like I said it is very difficult to do.