If you are on a JDM stock tune then you pretty much have to run 98 for best performance, they are tuned to run on 100 octane in Japan. BP is expensive though, so I run mine on either Mobil or Gull, both OK.
You can get it remapped to run on 95, but you will be losing out on some power and torque.
I am the biggest advocate of getting the H6 remapped, just because it made the car so much better. Stock tunes are rubbish no matter what fuel you run. I think post FL might be a bit better.