Some history about that subject: John Equi made the first stamped, two piece aluminum outboard pipe (as far as I know of) that had a bend that would allow the pipe to mount behind the engine and lay horizontally because a lot of people were trying to stick pipes on outboards back then that stuck straight out of the back and if they were very long they would bend everything that was attached to them in a crash. His best pipe for the 7.5cc outboard was called his Big Belly pipe. That pipe was made by cutting his smaller center section out and welding a larger diameter "Jim Irwin" style inboard center section into his pipe. John Equi helped a lot of people back in the day. You still see him come out to the Huntsville pond occasionally.
-Carl