Schumacher headers 440 in 71 Duster

How much power is the tri-y making more than a set of cast iron manifolds? Is it really worth it?
A lot more! comparable to 1 7/8 full length until 500hp and great torque through midrange.yes it's worth it if you ever learned how the tri-y works it's weird compared to conventional headers and yes full length with a 3" collector is better suited for higher rpm and hp applications but until your deep in the 11's tri-y is fine