As Bobby says, the base timing is set the same so it makes sense the Ignition map is different to benefit from the higher octane fuel in JDM.
Thinking more widely, the speed limt is an ECU controlled function so the UK ECU will have this removed. Probably other things too, Ed might pass through shortly and explain all the mysteries.
Ed, just thought, if you do, can you post up the standard ECU's ignition map as I wonder how that compares to the PFC? I found recently that has a few different "defaults" depending on what datalogit software you use.