differnce between 89 adn 91 octane canned tuens on 3.5l V^

[Tava]

like the title says. predator model U7136.

1. whats the difference? other than what gas I am "supposed" to use
2. benefits of one over the other?
3. dealer says my car is made to run on 89.. does that mean 91 can ruin piston rings, valves and such?> or was he referencing that the stock tune is made for 89 fuel?

Thanks

[Mike_Levy]

1. About 2 degrees of timing
2. A few horsepower
3. The dealer is an idiot. Once you change anything from stock, like the tune, what the dealer knows means nothing. Use the gas for the tune you're using, not what the dealer says.