The white in unleaded fuel means a lean condition, but when running a leaded fuel it will lend itself to add a white residue to the plugs even when on the rich side and also the inside of your exhaust with turn white also from the lead.
I raced ATV's and dirtbikes for many years myself and running extra octane in something that is lower compression is $$$ out the tailpipe. The smell is awesome and I'd pay an extra buck a gallon just for the smell!
I still need to get going on the design of the "High Octane Race Cologne for Men" !!:2thumbs: I think it would sell like wildfire! Smell like burnt race fuel.