I know my car is different, but in the GT500 supliment it says the trans can be noisey due the twin disc clutch. I haven't heard anything, much less missed a gear etc., As far as black stuff on the inside of the wheels??/ I noticed that on my front wheels also, right on the rims edge by the tire, like it scraped something. I figure it's a rack or something that holds the wheels as they move around the plant for instalation?? Wild guess, but, there's no marks on the inside of me wheels or weights.
So far all I hear is what sounds like a pulley that's NOT happy, it seems like a little grinding, but it too comes and goes.
So far my only real problem is my dislike for the key fob. The buttons are too small, and I don't like having to hit the trunk twice. Life is so tough.