Would these do as good as a HP OEM set of manifolds? How much HP gain or loss over headers do you think they would be? My 360 is a mild build, nothing radical. I'm wanting to put a whole new exhaust system (within a budget) in the car and just exploring options.
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1968-74 Dodge Plymouth 340 360 318 Exhaust Manifold Pair Clean Dart Duster Demon | eBay