Unless the design of the 650cc exhaust system's been changed dramatically for the new single headlight 650s, it's still basically a one-piece design- can and plumbing -(apart from the first 15 or so inches from the front cylinder) so a link pipe and slip-on won't do the job. You'll need a whole (" three-quarter") system. Having said that, once such an aftermarket system's been fitted, you could, I think, always swap to a different end can.
The 1000cc setup is completely different, and does use a link pipe and slip-on can as standard, so changing the can is simple.