i think it's still a downpipe. if memory serves me correctly, the catback would need the flange rotated. i wouldn't bother. the n1 is a little much for most people, i'd recommend getting an exhaust designed for the obs. I would talk to Garrett (GClark) if he's still around. his obs sounded great.
Who Me? Well I have Borla Unequal Headers, Injen High Flow Cat, wrx mid pipe, and a STI axelback. I wouldnt get that high flow cat, its supposed to increase hp, but its really hard to tell. check out boxer4racing.com that's where I got most of my stuff.