Sorry, but do you know about variable intake in A8? If you have long intake runner you have more power in low rpm, with longer intake is increase power in middle and high rpm. You don't need CAI in A8.Is done enough about that.
When is cooled just no need a high octane fuel. ECU is responsable for timing correcting, to safe engine of detonation.
pp look about
variable intake in 40V engine.