You are correct in your conclusion... And here's probably why... Per the Bosch MotorSports Rep., the knock sensors on this engine are VERY sensitive, any hint of knock, or even the sound of valves clicking will cause the ECU to retard the timing and fueling. Even if you can't hear anything the knock sensors can. Also, since our engine runs dual plugs which are rated on the "HOT" end, the engine is prone to a minor amount of pre-ignition, that's why they recommend 91 or higher octane fuel...

So by increasing your octane level you are preventing pre-ignition thus allowing the ECU to run your engine without reduced LTFT STFT and retarded timing...

It was recommend to me that I should use a isolation spacer between the knock sensors and the engine block to prevent the sensor from detecting certain valve tick and minor knock... I'm going to build one that will work on our car since none exist in the aftermarket...

You also might want to try a small amount of MMO in your fuel... It will help lubricate the valve seats and prevent varnish build-up like you have seen on my other posts...