I don't think you can buy the Y piece as a single unit.
If your handy with a mig you can buy the pieces needed to make your own from most exhaust shops (2x90* mandual bends, 1x collector). Just make sure they fit in or over the lcb's.
It is time consuming as you have to tac them together on the car then pull them off and weld them a bit more than refit and check again etc etc but it can be done.
On the note of making the Y piece don't get the exhaust shop to make it because it will end up costing near what a new set of lcb's would cost
