Used Exhaust Manifold Cover modified with threaded open ports that can have a pipe screwed in. We do not have the pipes as shown in the last picture which is for illustratration only. Do not think it will do much for performance but it will make a lot of noise.  One hole has an aluminum cover, the other three the cover is missing. I do not have any history on this piece.  Looks to be a Piper exhaust manifold.