Run premium fuel ALWAYS. Yes people have gotten away with using lower octane fuel, but by running say 87 octane they are increasing their KR quite significantly. You could run 87 in your car, but I would only recommend it as long as you don't go WOT till your next fill up (meaning practically running the take dry). Read up on KR and it's effects on your engine, it may save you from blowing your **** up in the future and will give you a better grasp on how to properly mod your car.