^^^ Yep, it seems that there isn't much room to add timing beyond the OEM maps.
Yet another reason why higher octane fuels on our motor are only really useful as a precaution for hot laps at the track on a haot day, and even then not critical.
The OEM timing maps are pretty good at self-adjusting -- it's prety hard to get this motor to ping, from what I've been told (then again, see this...
)