Originally Posted by E-Mann

As a follow up. I received the 6.1 standard rear tower. As I predicted there isn't much difference in the B6 and 6.1 tower. The B6 tower is about 1.5mm taller at the shock mounts. Pictures attached showing the difference. I will be using the 6.1 tower but would say if you are converting B6 to 6.1 it is not 100% necessary as long as you increase droop/ stroke at least 1mm to compensate.