When I put the HEMI in my car the first time I had an original set of 68 headers. They worked OK but for the street I found even with heavier torsion bars that they would hang down low enough to rub on the pavement on bumps. So I pulled them off and went with the cast manifolds. And another thing I wasn’t crazy about was the header leaks. I realize that they may perform better than manifolds but for running on the street, manifolds work great