you'll have to buy a complete system for your particular bike.
Otherwise look at the earlier versions and see if you can pick up the earlier models exhaust system.
It is going to be prohibitively expensive though as it is far easier and cheaper to construct a 2-1 exhaust than a seperate exhaust system for each side..
you'd be better off not bothering
or alternately finding an old exhaust can and installing it as a fake if you really want to go that way..