Using the "wrong" gas is a waste of money. Engines are purpose built and gas is formulated for specific engines. In the case of octane ratings, the short explanation is that it has to do with the compression ration of the engine.
Which means that "premium" gas is not better. Pure and simple.
All things being equal, the octane ratings for gasoline are an indication of what engine it should be used in. The Gen 1 Busa engine is built for 87 octane gas. Using higher octane or "premium" gas does absolutely no benefit to the bike at all and it has been shown repeatedly that using higher octane gasoline WILL reduce gas mileage and the power of the bike.
If you're using gas rated higher than 87 octane, test this out. To do so, do a run with your higher octane gas which will use up the majority of the tank and return you to your starting point. About 140 miles is pretty good. Then fill with 87 octane, run the tank out, then fill with 87 octane again and do the first loop again. You'll notice a difference. Note that it takes at least two or three tanks of gas to get the notable difference.
You'll stick to 87 octane from that point forward, I can almost guarantee it.
One thing to note is that there are suspicions that using higher octane gas than 87 can damage the engine physically but I've never seen any real evidence of that. The engines are built rock solid but they are built for 87, not 89 or higher.
Also, if you think you need to "clean" your fuel system, "premium" gas is not the way to do it. Use Sea Foam or Chevron Techron additive as a basic way to do so.
Bear in mind, "premium" is merely a marketing ploy that started back in the 50's or thereabouts and continues to this day.
If you want, ask me how I learned all of this.
--Wag--