Many exhaust shops wont touch it. Its technically illegal in most places to move the catalytic converters from their stock location, so many places just opt not to do it. As an example of just how rediculous it can be, we had an ORY for my friend's LS1 that we needed like a 3-5" extra section welded to it for it to fit correctly (this is before he invested in a welder). We took it to at least 5 places who turned us away and simply would not touch it. Keep in mind, we were driving around in a pickup with the Y in the bed, asking them to simply weld a small peice of pipe to the end of the Y, they never even saw the car let alone had to do the install on it. For all they knew it was a non-registered race car, they never even asked just said "nope, we wont touch it". I think we finally got it done by some race shop that builds little circle track legends or something.
My suggestion: buy the Y-pipe and install it yourself.

Theres going to be some form of Y-pipe anyway.