Anybody remember Extrude Honing?

I was reading an old Mopar Muscle Magazine the other day, and I came across an article about how someone had their iron exhaust manifolds extrude honed and picked op 10 HP. As I remember, extrude honing forced a thick, abrasive liquid though the inside of a part like a cast iron exhaust manifold and it not only smoothed things up, but it removed some material. I would think it would be useful for more than iron exhaust manifolds. Does anyone do it anymore. I haven't heard about it being done for quite a while.