Am I the only person that doesn't have a problem with their tuner? and I`m running an 89 octane. and a PCM will not relearn its old ways because you removed the factory tune and downloaded a new one. it cannot relearn what is not their. it will learn as it drives though. a good tune will add power across the rpm range.
If all you have done is read about then you don`t know anything about what a custom tune can do. ask anyone of us the has a tune from 5star tuning and everyone of us will tell you its the best thing we`ve done!