I've read that the 2.3liter is less torquee in NA because we use regular fuel, while it is tuned to use upgrade fuel in europe. Could we "retuned" the motor for it to use super grade fuel? (better torque, better mileage) I've heard that using super fuel in a "detuned" doesn't bring any advantage. So I hope the 2.3l can be "retuned" to use upgraded fuel. Anybody know anything about that?