It’s not often you see a pushrod engine under the hood of an S197 Mustang, and it’s even more unusual to see a 427ci Windsor. To spot a twin-turbocharged 427 under the hood … well that is a unicorn sighting for sure. Nelson Competition in Pinellas Park, Florida, built the short-block, while Real Street Performance finished up the top end and constructed the turbo system. With the twin Turbonetics GTK850 turbochargers at 10-11 pounds of boost, the combo makes a safe 730 hp to the wheels. RSP’s Jay Meagher thinks the combo would be good for 840 at 16 pounds, but the current level makes the car more streetable.