If you have any fabrication experience and lots of expensive tools, you would be better off fabricating your own exhaust. The stock Duratec exhaust is relatively restrictive, and hey, if you're going that far, why not go the whole 9 yards.
You'll need a welder and a mandrel bender. Take pix of the junkyard exhaust and fabricate your own system from right behind the flex pipe. Fabricate a Y pipe, which goes into two catalytic converters (remember, you'll need to put your O^2 sensors in, then a pipe to dual resonators, then to the mufflers. I would go with Flowmaster or Magnaflows. The Flowmasters sound a little raspy on the Duratec, but I think they sound really good on the Vulcan.
If you don't want to go to all this trouble, go to the junkyard and hack the pipe off right behind the flex pipe. Do the same on your car. Test fit all pieces. If you're going to all this trouble, you might as well replace the mufflers and the cat with a high flow setup. Modify the exhaust hangers as needed, mount, weld pipe behind flex pipe. You may need new exhaust hangers, which I think you can get at Autozone or something.
JR