Does anyone have experience with their Bravo one outdrive making a noise almost sounding like metal on metal banging at and above 4000 rpm?? I don't have any grinding when I turn so I don't think it's my gimbal bearing but could this possibly be a u-joint? Someone else also said that it could possibly be my exhaust flappers?? This didn't seem possible tho because I can't see them slamming shut when the motor is at that level of thrust?? It's a 496 Mag on a Baja Outlaw 25. Any input would be greatly appreciated

I had an internal exhaust flapper break lose.I honestly thought I lost the motor it was so loud.If it is the drive pull it problem should be pretty apparent.Could it also be?
Flywheel bolts
Engine noise