[Phantom]

Yes but that is a manifold that is tuned to have the pressure waves from two opposite firing pistons create exhaust scavenging from the pulses passing the crossover point. Then those two do the same when they join the other two on the same bank. Each junction is tuned for running at a set RPM range.

Also that engine does not get that MPG just from the exhaust but it runs a 14:1 compression ratio, has the long tube equal length headers, direct fuel injection, special dished pistons, and dual electronically variable valve timing; on top of that it has a 6-speed transmission.