I was racing my mate the about a month ago, when i missed a gear going into 5th and just revved the arse off of it, bounced off the limiter and black smoke everywhere, car seemed alright still, and thought nothing of it. but the other day my mate told me that when i floor it and change gear i get a puff of black smoke out of the exhaust, is this anything to worry about? and how do i reslove it? the car doesnt smoke at all when im driving around normally though! any ideas?