Hello, I have 03 LR Disco and lately I hear a high pitch (whistling) noise when the speed reaches 75 mph. The noise only comes on when I press the gas pedal around the mentioned speed. I though it may be the stereo but I hear it even when the stereo is off. It's been driving me crazy and can't figure out what is causing it. Does anyone know why this is happening? I appreciate any advise. Thank you!