96+ octanes usually have special additive which tend to damage cats and other parts. Lead being the most present for 110 octane. Sunoco Super blue(?) is an unleaded 104 I believe, but last I heard it wasn't doing good things with seals, read the disclaimer on the pump. I recall a 98 octane at marathon? but I do not know anything about it.
By excluding 96+ I was meaning to say any premium or ultra-premium gas at any altitude. Race gas is just too much for street cars, and is not worth the risk of cat/seal damage. Using higher octanes can ever hurt the actual engine block itself.
