When I nail it though it's all about the lovely thunk of a perfect contact.
Thanks very much in advance!
The spine does not flex or extend in the backswing. The motion you are referring to, the change in the primary spine angle, occurs because flexion and extension is occurring at the hip joint. Nobody has that much true spine flexion. Spinal motion can only take place at the L5-S1, unless you are changing the curves of your spine.
Sorry one more question, is it ok to lock your right knee or should i still keep it bent to some extent? Thanks