Introduced in January in Detroit at the North American International Auto Show, the new Porsche 911 Turbo and Turbo S (porsche.com) deliver more power than their predecessors and display revised styling. Both models are available as a coupe or cabriolet. The redesign includes a new front valance, narrower LED headlights, and an array of new scoops and aerodynamic details. Together, the changes lend the cars a sleeker look. For both models, the power output has been increased by 20 hp: The 911 Turbo’s twin-turb…