I think that's the conventional wisdom, but I'm pretty sure Nocturnal runs 88mm pistons. At least one US tuner believes in 88mm pistons, I think the quote was "that's 100cc displacement you're not going to get anywhere else, and displacement matters".
I have a set of HKS 88mm pistons if anyone is interested. They were in my engine before the rebuild, and I decided to go back to factory bore size. I cannot comment on power output, as I never ran the car with that engine.