I’ve noticed this whirring sound recently. Not sure where it’s coming from because I haven’t had anybody rev the engine up to 3k while looking around the engine bay or under the car. When I first heard it, I thought it was a gear noise, but then I tried revving the engine up in the driveway and still heard it. As you can tell, the noise is rev dependent and seems like it only happens around 3k rpm initially, but can be manipulated around above and below 3k rpm. I’ve noticed one of my lifters sticks at random intervals of cold starts. I assume it’s an exhaust lifter since it will actually effect the sound of the exhaust. Makes it sound like a Subaru. Any thoughts? It’s a 2006 MCD 6spd manual.