Hey guys, I have a 2008 cts 3.6 DI. Recently I noticed that it makes a constant ticking sound upon ignition and the sound seems to also effect the sound of the exhaust, making it sound "rougher". The sound seems to be coming from above the engine towards the cabin of the car.The sound does not seem to go away after it is warmed up, but does diminish. It only has 44000 miles on it. Otherwise I have noticed no difference in performance. Anyone have any ideas on the issue or have past experience?