The 6.7 Power Stroke engine in the 2015 Ford F-250, F-350, and F-450 picks up a massive 40 horsepower and 60 lb-ft of torque thanks largely to a exhaust design that happens to look like a scary snake.
The new exhaust system is setup in what's called a "reverse-flow layout;" placing the exhaust inside the engine's V-shape while the air intake is positioned on the outside.
As you probably know; a turbocharger is basically a sucking-system that's driven off the engine's exhaust system. More exhaust, more suck, more dense fresh air coming into the engine's intake, more power. So a shorter airflow from the exhaust to the turbo means those exhaust gases won't lose as much speed or density spooling the snail (turbocharger) which means better responsiveness and more power.
Ford says they're also seeing "reduced noise, vibration and harshness" as a result of having the turbocharger bolted directly onto the compacted graphite iron engine block within the V of the V8.
So Why Is It Shaped Like A Cobra Head?
Robert Wade, Ford's engine air path technical leader, explains; "Fluid dynamics allowed us to precisely tune the curvature and width of the pipe to optimize exhaust gas flow. It turns out that a downpipe shaped like a cobra head is the ideal design for air flow and breathability, which we validated through thousands of miles of durability testing."
Basically the cobra head lets the exhaust gas flow around a 90º angle more smoothly because it makes a widened, banked turn as opposed to a full-stop kink. It's a nice improvement over the outgoing shape while working around the same tight space.