The foundation of the Doug Thorley Tri-Y headers is the 3/8-inch-thick header flange. The 1-5/8-inch-diameter 14-gauge mild steel primary tubes were mocked up using 14-gauge J-bend tubes.

Run on our Mast-headed 427 LSX engine, the Hooker long-tube headers improved the peak numbers from 661 hp and 564 lb-ft of torque to 681 hp and 578 lb-ft. The peak gains were nice, but the headers ...

The Headers by Ed kit includes an assortment of mandrel-bent U-bends and J-bends, collectors, reducers, O2 sensor bungs, cylinder-head flanges, and some straight tubing.