Header Questions for a 73Duster

Went to Summit site today and heres what they show:
Part Number: PTE-H8206-1

HDR MOPR A BODY SBM 67-82 CTD

More flow equals more power.
These full length chassis and fenderwell headers provide the ultimate in performance for street rods and musclecars with high performance engines. The key is their use of long primary tubes, which result in more horsepower and torque than those from the competition. Other features include a close fit with the engine block for maximum chassis and steering clearance, mandrel-bent tubing that's available in your choice of bare or ceramic coated finishes, and new gaskets and bolts.

Makes ya wonder