CJK

I need to update mine and reprogram but so far I haven't noticed much difference in power but I'm only on my 3rd tank. I also haven't tried the premium program yet so the jury is still out.

JPop

With an automatic transmission you should be noticing better seat of the pants performance with shift points and torque converter lock up management. Power is very much debatable, especially for those who have made intake/exhaust performance enhancements prior to the installation of the Hypertech. It very much seems that the intake/exhaust/programmer have diminishing returns as you add more of them. The first upgrade you do is likely to provide the biggest performance pop, and from then on likely less than advertised.