It's all in the tune... And fuel quality and IAT.

Btw - I'm running the off-the-shelf Probe pistons in mine now. The stock pistons and rotating assembly never failed, but I knew that after putting 16 psi with some occasional spikes to 18 psi or more for the past few years - that it was on borrowed time. I didn't care about the pistons, but knew that I didn't want to go looking for another block if I pushed to ultimate failure.