Okay gents-I tip the scales around 250 but I can't believe I'm the only one having this problem. The dealership where I bought it got it done (driver's seat frame replacement) at 38K becuase I made enough noise about the fact that something just didn't feel right in my seat. It felt like the seat wasn't properly locked in when either slowing down or taking off from a light. The first time this same problem happened, it was two months after I took delivery and at that time they fixed it without much fanfare. This time around the service manager there said he was confident that was the LAST time GM would address this issue for me. Not real comforting over what appears to be a design flaw in whomever NUMMI contracted to make the seats on this vehicle.