Extrude whore does not port, it polishes the inside surface. Depending on the material , it will remove surface metal but not much. Extrude whore didn't remove that much material on my cast iron exhaust manifold. If you have a big bump on the inside it becomes a slightly smaller polished bump. I had mine ported and extrude whored. It usally compliments porting but does not replace it. The price is of course rediculous high when you consider what it does and does not do.