@Andres4NY @agegamon That back-to-back tandem recumbent was designed by Kurt Ritchie in Richmond, Indiana as a one-off. He's an acupuncturist by day who also knows how to weld. The chain crosses over at some point so the stoker can also pedal "forward". There's also a freewheel that allows the stoker to idle if they wish.
Besides the exhaust pipe from, I believe he ordered some chromoly tubing from airplane supply company.
The shape of the bike does make it aerodynamic and fast!