[Oldsguy]

Oh ok, I see. Well, Oldsmobile advertised many of their engines at or above 350 hp in the late sixties and I don't think they ever used 3 inch pipes, for what that is worth anyway. As Norm has said, advertised numbers are just that, take if for what it's worth. I had 3 inch pipes on the '69 Delta I used to own and all they did was make the cabin loud at highway speeds.