Here's my slip. Apparently I need to go home and practice launch control. I've been reading up on it and its possible I wasn't hitting the gas quickly enough to the floor to get it to kick in.
Another thing I saw about launch control is that the car may be short shifting first to improve acceleration.
Has anyone heard of getting bigger turbos for the M5? I saw an M4 video with some built up turbos. Maybe it'd make a better track car. I tested out an M4 once though and thought it wasn't what I was looking for.