Apexi PowerFC retune from RON95 to RON97, Nissan Cefiro A31 RB25DET NEO

After countless headaches on diagnosing the issue of why my engine was spitting back then, it was actually just the spark plugs even though it has been inspected and was claimed 'healthy'

Changing all 6 of them to another second-hand spark plugs by my other friend, causes my engine to start knocking with the old RON95 tune. So I went to find my friend for a second round of tune, this time with RON97

RB25DET NEO has a higher compression ratio than the older RB25DET's used by R33 GTST's... After surveying all of my friends that owns a Skyline engine, non of them runs RON95, I guess I was the only idiot that runs this setup, even though RON97 is more expensive than RON95 for about 18% as of today...

Time to move on, I started driving around clearing the RON95 petrol and filled RON97. My friend did his magic for about 5 minutes while the engine was off. After that we both went for a drive.

First he asked me to park roadside then rev to 1k, 2k, 3k, 4k, 5k, 6k rpm... kinda like step by step to me. Once it was done then we both went to some highway to fully test the potential.

It was still knocking at gear 2 at about 5k rpm at full acceleration. Then he continued his magic touch from his laptop while I was driving.

Even though I understand how engine combustion works, I still have 0 clue on how to tune the engine by myself by using a laptop and an adapter that costs RM1000++ just to connect to my Apexi PowerFC ECU.

After everything was sorted out by him, no more knocks. I can actually feel the engine has a better response and the rpm goes up way quicker than before when I was using RON95. Last dyno was 264 wheel horsepower for RON95 at 1 bar of boost, not sure for RON97 how much higher it'll be, I'll go for another round of dyno some other time...