Originally Posted by BMW-M-Mexico
Hmmm! Funny. Where is that dyno? Somehow I doubt that is true. What may happen however is the anti-knock sensor "senses" knock and reduces timing etc... automatically (We now the M3 engine has this sensor). And, for instance, when using lower octane fuel than 93 (that is where the engine is tuned stock), the hp produced will be somewhat less than 414bhp DIN. When the proper fuel is again administered, the engine will not sense knock and will, in time (by no means in a few minutes), return to its regular tune. This may explain why you feel a power increase with improved gas (because somehow shitty gas ended up you your engine) but when using say 104 octane, there is no way the engine can "retune" itself to produce more power than where it is optimized from stock which is 93 octane.
Not sure what there is to doubt, how do you argue with the dyno numbers? I decided to try it myself, made a difference. You got it right and said what I did, the motor does not have to retard timing with higher octane. These ecu's are highly sensitive and adaptable.