Im getting a protune done and not going the route of getting an AP. Also with the stock turbo, the only thing you are really going to get when you add an exhaust after replacing a dp is sound. The power difference though should be very noticable from stock to stage 2. From talking with tuners though and looking at dyno runs, it looks like a stage 2 setup with the AP should get you roughly around 300awhp with your sti.
Fotown that does help! Still hoping to find an audio clip or video though because im very impatient!