The one from E-bay has to be modified in a few ways. Weld the bottom part to the collectors. Cut the O2 bung off that they put on(its wrong in every way possible), and weld a universal one in just behind the "Y" pipe that gets welded to the collectors. Drill out the bolt holes in the flange a little so that they fit better. Grind down the front of the flange so that it clears the coolant housing under the distributor. All in all, took me an hour to modify it without welding the 2 pieces together. I didn't learn that lesson until it came apart while driving home one night...
The OBX piece that connects the header to the cat is 2 1/4", but I think 935 replaces it with 2.5" . If I'd have known about his, I would have bought it from him instead. Paid $305 shipped for mine.