Hypers are factory on many turbo cars, but this is dealing with an engine that was never meant for a turbocharger. There ok for N/A street motors, but in cases like custom turbo's and NOS, the tops can split right off them, I'v seen the aftermath. a Cast pistion will hold better under preassure than a hyper, but even better than a cast, is Forged. it probably wasn't just the turbo that caused faliure, but possibly a mix of high rpm, and the turbo. possibly even a small crack never noticed b4 ( defective pistion ) when it was built.