Ah Saw, what other exercise gives you thoracic rotation, side bending and flexion (oh! corkscrew yesterday, well, this is a lot easier to achieve). Sit on a roller to make the movment about the roation, sidebending and flexion and not about how uncomofortable siting in neutral can be. Focus on the movement, take is slow then speed it up. Muscles fibres like different speeds to train them all.
Primary focus: Thoracic Mobilization
Secondary focus: Lumbopelvic movement