Ya, I remember now DP using the stock STi axle back/muffler. Keeping the Stocker will rob you of a little bit of power. As for the raspiness, I am unsure.
However, I think you should look into a full Catback w/DP. Maddad Whisper is a great/quiet exhaust and IMHO is one of the best on the Market. It also comes in a twin tip or a single. Borla Hush (which I own) is also another great choice with low sound levels in mind.