You mean they learned how to drive the same track better in the same evening and took 2-3 tenths off?
IMO, there are three leaders who tune Mustangs: Steeda, Lund and Bama. A lot of people are very happy with Steeda and Lund, so I doubt there are safety issues with them. However, if you're running tunes and not maintaining your car, well yeah, you need to take care of it since you're pushing more of the limits (not really since it's not FI). Even the Bama tunes are more aggressive than stock, so if you're hinting you don't need to take as good care of a Bama. Tuned car compared to another tuner car, then I'd disagree with you.