Ok, the legacy style is by far the most expensive, and is a bit better.
What I would do is make a custom setup, with the stock Y-pipe cut not far after the 90 bend. then run it up behind the subframe to slightly above where miniam puts thier turbo. Use a common 2-1 colector to make the transition. Then reduce it to the diamiter of the turbo, and put a flange on top. If you want me to I can make the flange needed for athe early Subaru turbo turbocharger or the legacy one. I have MOST of the dimentions needed for the legacy one, and all of them for the early Subaru. The downpipe flange is more difficult but can be done.
here is a few pics of the one for my Hybrid Wagon.
http://web.nmsu.edu/~ewitte/subhdr_2.JPG http://web.nmsu.edu/~ewitte/subhdr_3.JPG http://web.nmsu.edu/~ewitte/er27man_1.JPG http://web.nmsu.edu/~ewitte/er27man_2.JPG http://web.nmsu.edu/~ewitte/er27man_3.JPG
Note If I had to do this again I would have used a WRX turbocharger, and mounted the turbo farther back and slightly lower.
As seen in this next pics the Turbocharger I used is off of a single turbo Supra.