Hello! Thanks for this great forum. I picked up this CPO 2012 LT fleet for a very good price about a month ago (Love that first year depreciation!). I'm enjoying the power and comfort, and still getting used to the car. I have noticed a couple of issues. There is an unusually loud noise from the engine or exhaust when I'm accelerating under load from a stop or low speed. It sounds like an exhaust leak or even a possible restriction, although none has been found. There's not a distinguishable knock or tap, but more of a breathy, muffled growl that has a rhythm to it, but it's loud and unnatural enough that it makes you immediately think something is wrong under the hood. This almost new family car shouldn't sound like it has a Holley 650 with all barrels wide open, when I'm just pulling out of my driveway. Both the service department at the lot where I bought the car, and at a GM dealership have looked at the car and both said that's just the way the car sounds. I find that hard to believe, but so far I'm not educated enough about the car to argue with them. This noise only happens under load, and it smooths out and disappears above 2500rpms. There is a definite cadence to the noise that changes with the rpms. I've eliminated it being associated to any suspension parts. The noise only happens under load. When in neutral or park, the engine revs smoothly and no noise can be heard, and the transmission seems to be working correctly. My second issue is with the starter. The starting is rough. It knocks and shakes pretty hard when you crank it. Usually a couple very rapid shakes, a thump or two all within a quick second, then it starts up. It has never failed to start, but it definitely seems like there's a problem with the teeth alignment and it almost feels like it's trying to bind up for an instant before it angrily starts the car. I've done some research and asked the service departments about possible starter/flex plate issues, wondering if these things are related, and if there's something throwing things just a little out of balance under the hood, but no one has been willing to tear into the car to see if there are any deeper issues. The car seems to be firing just fine with no misses. I have about 5k miles left under factory warranty, and am anxious about not getting my issues addressed before my warranty expires. Any opinions or advice would be greatly appreciated.