Metal on Metal sound

[Steve Stevanovich]

I have a 2019 Mustang GT Convertible which I purchased new. It only has 6500 miles. When I first crank the car I let it go from 1200 RPM to 800 RPM before putting in gear. Then when I put in gear I get a horrible metal on metal noise. Once the car warms up I never get this but it always happens on a cold start. Any idea what this could be? I'm going to the dealership tomorrow but I just don't trust they are going to give me the straight scoop.