The higher the octane, the slower fuel burns. Remember, it is a rating. It is a matter of personal choice. On a turbo motor, you will have to use a good fuel, but just how good is another story. I have tried just about every fuel known in the free world, all with different results.
Nobody wants to go to jail for messing with the quality.
Then there are legitimate vendors. Our buggy group has mixed and matched, added our own blend of snake oils, etc. You are free to try whatever, but all I ask is do real measurements on performance when comparing and not by some wanna-be speed shops recommendation. Read about the makeup of fuels, how they burn, and educate yourself.