Have used 120 ron & could not get det even at 26deg ignition but way too agressive. Now use higher compression & 109 to keep cylinder pressures under control.
They are not supposed figures if all you want is Power, mine is still very much a compromise to aid drivability, relatively small ports (way below 27mm) mild exhaust cam & standard valves. Power is not a problem but difficult if you want to drive the friggin thing.