I have a 2011 legacy that is a single exhaust and I want to make it a dual exhaust. I have a dual exhaust from a 2008 legacy and was wondering if this would fit or could be made to.

You have a 2.5 4-cylinder engine, you don't have dual exhaust, can only use the dual cat-back setup, if that is what you want. Any muffler shop should be able to put this together, without breaking the bank.

Yes, you can do it, but be sure to use the aftermarket gusseted rear Y pipe instead of the OE to ensure longer life of the corrosion-sensitive crotch. In other words you're asking for trouble, with no perceivable gain in performance! Only the turbos or H6 benefit from twin mufflers slightly reduced back pressure. But if you insist you can get aftermarket rear Y for about $200, plus $100 each rear muffler, plus about $40 in gaskets. So figure $600 installed inc an hour labor. Absolutely worthless mod....