As Japan have way better fuel than us I'm guessing these car are setup for the high octane rating. Japan is like 100 RON with there octane rating or maybe higher even? I am told lots of car can tell and adjust to what type of fuel we are running, If we use crap fuel, the car may detune itself so you would need to run a few tanks of good fuel so it can tell it's good fuel and then run at peak performance. Which brings me to the point of octane booster and AVgas. I have used a good octane boost in a turbo before and it does make a difference I found it had smoother power and maybe a bit more or was it in my head? Yea smoother power for sure. AVgas uses small amounts of lead has a much higher octane level and burns slower. A guy at work used it in one of his cars for a full 100,000 km's and had no problems. Anyone know if there are any side effects if let's say for example only I was to use a few tank fills of avgas in the Legnum? Its agaist the law so lets say for an example only. Also I have been told BP is better than shell has shell have additvies to make the higher octain ratings while BP is refined at a higher octane level.