I have a 2000 Legend TT - Green Goblin. I use 89 octane or mid-grade - the bike runs very well and gets approx 48-52 Mpg on open road at 60 mph. No backfiring or burbeling in the pipes. I have tried 87 octane and it runs OK but you can tell a difference in performance and mileage.
Even taching as high as they do they still get very respectable fuel results.
