I have a 2008 WRX. Only has 10k on it. I have noticed that immediately when releasing the clutch off the ground, and the clutch engages, there is a single knock noise and you can feel it happen underneath my clutch foot. Subaru has taken the front joints apart, greased them, changed the torque settings and nothing has worked. They cant seem to hear what I am hearing tho. Does this sound familar to anyone else. Hopefully I'm explaining it well enough. The car does seem to have any negative effects from the cause of the knock, but it may contribute to some down the line. Please respond if you have ever incurred this problem. I have had the car in 3 times in the past month and they cant fix it.