I can tell you from my dyno tune this week, some cars don't like timing as much as others. With the "normal" timing settings on Brenspeed's 93 octane tune, my car ran very well but occasionally would have spikes in the upper rpm range while on the dyno; it was the knock sensors pulling timing out. Brent retarded the timing slightly and the spikes went away, and I gained 2 peak horse.
Since I always run 93 premium, I doubt that actual octane was a problem compared to other people. Maybe the cams weren't dead-on from the factory.