that was nice...

B-pipe is the part of the exhuast that starts directly after the cat and continues to the bolt on section of the muffler. Flanged, meaning the piping has a flange welded on so additional piping (or a cat, in this case) can just be bolted on, instead of welded - which is a choice also)
If you can cut and weld, you can do it yourself. Cats go for all sorts of prices - check ebay, online stores, etc