Colin, I have been driving with the Stage 2 tune since I've got them and as far as shifting, the only difference between stock and the stage 2 seems (to me) to be: 1.) Shifts seem to be a bit firmer and quicker. This is most noticeable under heavy or wide open throttle acceleration. Under normal driving the car still seems to shift firmer and quicker but if you had not driven the car and gained some seat time, I doubt that you would notice the difference in normal driving. I love the Stage 2 tune, will probably not use the others (although it's great having them in reserve) until I get a wild hair and install the stage 4. I love the whole package of the Stage 2 and since my car has less then 8500 miles on it, I'm really thinking the Stage 2 works great I would upgrade to the Stage 3 or 4 if I were going to the drag strip, but since my wife said this is the last car I'm allowed to buy, I'm sticking with the Stage 2, it really makes this come alive and I like the way the transmission shifts with the Stage 2. Disclaimer: If I were single and didn't have any kids(or wife) who drove my car, I would be into the Stage 3 or 4 in a heartbeat. One last note, I just informed my wife that the SHO must have premium fuel ALL THE TIME..I got the rant from her..it was a "yes dear" moment.