First off all, I am really new as far as owning and driving a Mustang so I am not sure if it is normal or not. Anyway, Yesterday i tried to see how quick my car would go from a stoplight going to enter the freeway. When i shift to 2nd and at 3500 to 4000RPM i notice this weird rumbling vibration noise before i shift to 3rd. Is this normal? I think it is just a noise rumbling more than a physical vibration because the steering wheel is not vibrating but you the feeling of the engine trying so hard causing the noise?