Originally Posted by -=Hot|Ice=-
It's just too much power for the car to handle. 444 lbs of torque through an open diff is a recipe for insanity. The C63 doesn't even come with an LSD standard! The P31 Development package which bumps up HP to 481 HP is what gives you that.
P.S. You have a C63 so you already know this.
You can get the LSD without the P31.