Temperature, elevation, and driver experience make a big difference, but I'm afraid I have to wonder about that 15.67 as well. If Josh Jacquot (Sport Compact Car) can get 15.7 out of an RS (best run out of may tries) then I'm willing to entertain the idea of 15.67, but I have to be a little suspicious.
Your times look fine for an automatic and a first-time at the strip. My times normally range from 16.2 to 16.4 (MY00, 5-spd), although they're getting better as I get more practice (and as the weather cools down in Phoenix). A friend, who's a better driver then me, has gotten in the 16.1's with my car. It's practically stock with the Subaru/Brospeed exhaust and a K&N filter.
Scooby's not a straight-line beast. Take him to the autocross. That's where I'm going this weekend.