Last Sat my wife backed the HHR out the driveway and drove away. I was in the yard across the street with my neighbor and another corvette owner. You could not see my garage when she left. We walked around and the corvette owner said that was the HHR she drove off in I thought it was the corvette, that sound from a 4 cyl?? Told him it was not the stock exhaust his reply was that sounds great.