I own an 04 civic and my girlfriend has an 03 si and we're both having the exact same problem. I talked with a friend from work who is pretty mechanically inclined and he suggested to adjust the oil pressure for the clutch cable. He showed me where the rubber pressurizes when you push the clutch in and there is adjustment screws on that. I'm kinda weary of trying that though. Does this sound like it might be a solution to the chattering