The Spoon shits over the BC Spec III. It's a REAL japanese made, racing exhaust for N1 Racing in Japan.
Jim was saying that it will only make noise if you put the axel back (c-pipe on) - even then it will flow slightly better. But with the header, nice cat (or JDM itr cat), Spoon B-pipe, and spoon axel back... it will be an awesome exhaust. Teamed with an ECU and a good intake, it will be great.
The difference is:
* Spoon N1 exhaust, sold as 2 seperate items Axel back and B-pipe.
* BC Spec III comes as a total catback together (b-pipe and axel back).
End of the day a pipe is a pipe, as long as it follows the most direct bends to the rear of the car, and bends are mendrel bent (not press). Resignators on Japanese exhausts have been placed strategically to increase air flow as well as decrease noise slightly. If you get a "custom" exhaust made in Oz, the resignators placed in random places will just screw everything.