What determines how much timing you can run on pump gas and race gas is your
compression
factored in with the amount of boost you are running. I dont remember off hand but i know there is a formula for a person's compression UNDER boost....just dont remember sorry
Maybe i can help you understand this way:
The only thing higher octane gas does for an engine is lower the tendecy for the engine to detonate because the higher the octane gets the slower it burns.
So think about it, if the HIGHER the octane burns SLOWER, you can run MORE TIMING before the complete combustion has occured and not be detonating. That is why under race gas you can usually run more boost and timing and that results into more power.
Basically you are going to have to figure out how much compression you are running at full boost and take into account the cooling effect of your intercooler and come to a conclusion.
i hope i've been able to shed some light on this subject. the same also goes for n20 and N/A motors, more octane burns slower allowing more fuel and air to enter the chamber before it combusts resulting in more power.
That is why you can sometimes run even a 11.8:1 on the street with pump gas because the timing is rather low.......put some race gas in it and turn the total timing up and look out!