Funny, as I read this we're just mopping up the last 2017 Malibu with the 1.5l turbo engine in the fleet for-#17019-01: Customer Satisfaction Program - Stochastic Pre-Ignition (SPI) Causing Cracked Piston - (Mar 2, 2017) .
My point being, nobody has more information and data available than the OEM manufacturer and even they make mistakes from time to time. The CSB above involves a PCM re flash fix and full synthetic oil change. Fully knowing this, I'm most likely going to go with a tune from one of the "L" company just looking for moderate gains on my daily driver. The thing is, whoever you go with is just an educated guess based on whatever information you can find but ANYTIME you monkey with the vehicles calibrations YOU accept the risks. I'm not versed on performance tuning and what items the tuner has at his disposal to tweek, but if the people that designed the car can make a calibration error that causes piston damage, it's just a crap shoot with any tuner. If it's true SSi turns off the knock sensor output, that's a big failsafe gone bye bye. I'd ask the tuner everything you have concerns about, then make a decision based on what your ultimate goals are and the depth of your pockets.