There are two types of Corvette brackets, shared drive and dedicated drive. 
Shared drive comes in six and eight rib versions and uses one long belt that runs the accessories and the blower.  The longer the drive belt is, the more it will grow as power is applied to at higher rpm levels which causes belt slippage. The eight rib version of the shared drive requires replacing the accessory pulleys to eight rib.   
The dedicated drive runs a separate belt for the blower and comes in six, eight and ten rib versions, and the drive belt is short. By adding a direct drive belt system to the ProCharger, they were able to decrease the overall length of the belt by over 40%, creating an ultra-strong grip.