I'm putting dual exhaust on my 99 V6. Takeoffs from a 99 GT from Saleen for $40 plus shipping, currently in transit. I believe the 99 and 00 are pretty much identical so I can tell you what I've learned about the 99.
I believe you can put any duals that will fit on a GT on your V6. But since the GT has more cats than a V6, the duals will come up a little short. So you must have a custom piece made (H or X or straight) to fill the gap between the mufflers and cats. PaceSetter makes an adapter but I've heard that it won't fit the 99-00. I'm not sure what it's gonna cost for the custom piece yet, but I've heard it will be about $100-$150.
Take a look here:
http://members.home.net/pfand/exhaust.html
Good Luck