TRANSMISSION and DRIVETRAIN

 Your 2009+ Cadillac CTS V has an amazingly strong drivetrain right off the showroom floor.  The 6L90 transmission and T6060 manual counterpart seem to be able to handle 600-650rwhp; however, going above that will have you looking for a built transmission before too long.  Once you start approaching higher HP levels with upgraded engine and transmission parts, you need to address the drivetrain looking at Chromoly or Carbon drive shaft.