My son's '06 R53 with six speed has an interesting issue, He was home for the weekend and he said that when he accelerates there is a pull to the left. I took it out for a drive and it does pull hard to the left during acceleration but goes perfectly straight all other times. It handles and steers well too. A few months ago, I replaced the drive shaft on the drivers side, could it be possible that the clip that holds the shaft in the transmission may not be holding? Could that shaft be pushing outward during acceleration? That is the only thing I can think it might be. Thanks for any advice and opinion.