Im changing my ls auto to manual right now, can't really tell you the power difference, but put it this way, if your running low 17's or high 16's with your auto, then you will definitely be able to run high 15's after changing it to manual. You could send your auto transmission up to a shop that was in south cali somewhere, and they will make it more consistent, but they charge you almost 3 grand just to do it, so its best just to go manual, auto does not belong on a sports car, especially one that is 4 cylinder automatic, so it would be best to change it to manual, and you wont be dissappointed about the power gain to the wheels.