If you look at the 1LE dyno thread they are putting mid 390s to low 400 Hp to the rollers. This is on average about 15 Hp more to the ground than previous SS cars. I haven't seen numbers for 13 SS cars but I suspect they make more than the 12s as well since the EPS came standard for 13.
If you look at the 1LE differences you will find your answer. All of the little parts add up to better acceleration and a lighter feeling car.
Delivered 21 Jan 2013