Header Q's August 08, 2006, 12:27:35 AM I realize that the stock HO headers are pretty restrictive but are they really that bad? How much better than the stock SO manifolds in HP gain and how much worse than an aftermarket in HP gains? I realize it depends on what aftermarket brand but i'm just wondering roughly how much.Thanks guys/gals Quote Selected
Header Q's Reply #1 – August 08, 2006, 01:13:41 AM I read somewhere that the stock restrictive mustang header is 7-10 HP more than the manifold. But it is restrictive so while your there might as well replace it. Quote Selected