I did this. I had it off last weekend when I put the TC in and wish now I had taken a pic of it. Took two FlowTech cutouts and a Flowmaster merge collector and had one made at a friend of mine's shop. Also took a pic of the $600 one so he could have an idea of what I wanted. He put the cutouts about 10" to 12" or so back from where it connected to the headers so its a little different from that one. It cost me something like $140 or so total... that’s including the cost of the Flowtechs and merger collector. Keep in mind it was a friend of mine and he worked on it for a few hours making sure everything cleared so I don't know how much it would cost at an exhaust shop to have it done.
So now I have 3" pipe from the Hooker headers all the way to the Corsa catback... plus I added a couple of QTEC's later on.
Word of advice, if you are going to have a y-pipe made and going to/plan on adding electric cutouts make sure you have enough room under the car for everything to clear everything else. Space is limited in some areas. After I decided to put QTEC's on, I had to take the pipe off and move the cutout part about 3/4" back from where it was originally because the QTEC hit on the sub frame connectors. Should have planned ahead a little better and would not of had that little problem.