High Pitched Squeal/Whistle During Acceleration

Hi Everyone,

I've been reviewing this board for some time now see if someone else has this problem. I bought my 2009 LTZ 4cycl in mid March. Almost imediately I noticed a high pitched squealling noise appearing around 2500-3000rpms everytime I accelerated from a stop. I heard it in gears 1-3 and possibly 4.

So I brought the car back to the dealer at only 380 miles. They told me that they were having trouble hearing it and that something might be breaking in. So I left, knowing that I was still under warranty and drove the car to 1300 miles until I brought it back to the dealer. Now the noise was louder anf I had gotten pretty good at reapeating it at this point. They took the car and tried to figure it out. The service center replaced the flex joint on the exhaust but the noise was still there. They did numerous tests and tried to repeat the noise on a lift but unfortunately it only happens when the engine is loaded (wheel torque).

They kept my car for a week. On the 7th day they had a GM factory rep take the car for a spin. He said that the noise was "not a problem b/c it didn't sound mechanical. Probably in the exhaust somewhere". This upset me greatly b/c there is not a single person who hasn't noticed this sound when riding in my car. The sound it some sort of vibrating part which seems to resonate at the mentioned rpms. It is SO ANNOYING! It sounds very similar to the noise breaks make when they wear down.

The rep said that he wanted me to drive the car until the first oil change and then have a GM field engineer check it out in 3 weeks. So, I still have the car... and I love it minus this noise! Imagine hearing nails on a chalk board everytime you accelerated from a stop.

Does anyone have suggestions? Is this a lemon? I really appreciate any feedback.