You got the answer, off set in, center out. I might add; The Flowmaster Delta 50's will fit but they require a bit more talent to install. (As I'm told.) As the story went, the input and output pipes need to be trimmed back a little. I'm not quite sure on this. I'm checking another shop before this happens. (This will be the third system in as many years.) Bottom line, be careful when deciding on the shop you'll use or go slow and sure if you do it yourself.
Currently I have a dual Flowmaster Delta 40's and the interior resonance is just too much. I just purchased the Flowmaster Delta 50's and I'm waiting for a Dr. Gas "X-Pipe" and the rear tailpipes. The Delta 50's need to be cut, trimmed and snugged in. I hope this will be the "tune" I'm looking for.