On the inside of your fuel door is a sticker that reads "Premium Fuel Recommended" - being in Oregon you wouldn't see that as regularly as those of us that get to pump our own gas. <img src="/forums/images/graemlins/lol.gif" alt="" />

I've found that my 95 gets roughly 1 mpg better mileage when running premium fuel, and it definitely makes more power - your results may vary. If I were you I'd track my fuel mileage through several tankfuls of regular gas and compare it to several tankfuls of premium from the same gas station, then its just a matter of personal preference - to me the improved acceleration is worth paying extra for, especially since it's slightly offset by the better fuel economy.

You shouldn't experience any knocking or pinging if your knock sensor is working properly - the ECU will retard the ignition timing if it hears any knocking, which is why the engine makes less power on the lower octane gas.