I'm wanting to ditch my OLD low hanging headers, are these manifolds worth it?

318willrun said
headers will provide more hp, the difference will be how mild or wild your engine is built...

Agree, i researched the same question and the estimates were 10-20 hp on a street engine. If IIRC a dyno test figured of headers vs the 68-71 factory 340 manifolds
Was only 8 hp difference.