FWIW, this is what I was told about cat-backs for our cars.
(1) The stock TI catback is considerably lighter than the stainless systems people are installing - unless you want to spend a lot of $ on the Corsa or Borla TI systems
(2) The stock Z06 systems flows a little better than the standard C5 system.
(3) Performance gains for cat-backs are quite modest, most people do this more for looks/sound.
(4) For those of us with '02s , the exhaust sound has changed and is considered "perfect" by many of us.
Now, IMHO, as an '02 owner, I have no interest in replacing my TI system with a noticeably heavier stainless system, which will make only a few h/p more - especially when I already think the exhaust sounds excellent. I would rather put my precious mod dollars into a set of quality long tubes - and that research is ongoing!
Silver, I started that thread and after realizing some folks were interpreting this news as a radical new '03 Z06 or whatever, I made it plain (0r so I thought) that this news pertained to the prototyping effort of a new mod. It still does. Unfortunately, as these things so often do, the effort is a few weeks behind schedule. The individual whom I am discussing this with (the developer) has solicited a promise from me that I would not divulge this info in specifcs, since this could cause him some problems. I intend to continue keeping my word to him.
I continue to believe that this item may be of considerable interest to many, once it finally sees the light of day - I know I hope so.