EFI systems have knock sensors that detect tope (knocking, pinging, detonation; pre-ignition is totally different and is a whole lot more destructive) inform the computer so it can automatically retard ignition timing. Some EFI cars have adjustable spark timing while others dont. If the timing was set correctly (for those with adjustable spark timing), it's only a matter of following the manufacturer's recommended Octane Rating for your car. If the car still knocks (it shouldnt, regardless of how you shift), then the fuel's octane is not really as is advertised.