You can make the Timing Advance in the Rx8 work like Turbo does by setting the rpm range that it happens at.

Turbo in our controllers is triggered by being at full throttle. Timing Boost in sensored and Timing Advance in sensorless are based on the RPM range you set. So if you know you are hitting 32k rpm on the straight you could set Timing Advance with a rpm range of 30k to 34k. The unit would start adding the Timing Advance when the motor reached 30K rpm and add all the timing you set by the time the motor hits 34K.

Should be basically the same end result as doing it with a turbo setting.