If your priority concern is warranty, keep the car stock. If you're wanting a night & day difference in your car's performance with minimal risk, tune it with a reputable tuner. I've had a Steeda 93 octane tune since 1,000 miles. The car has 22,000 on it now and couldn't be stronger. My dealer is cool as can be but if i fry a valve or piston, i dont expect them to cover it eventhough at this point it definiely would not be steeda's fault. You just have to decide your priority and personal risk/ reward factor.