The Porsche 911 Turbo S Cabriolet is a droptop rocketship
1 of 35 James Chrosniak/Roadshow The Porsche 911 Turbo S Cabriolet is so quick it'll make your brain hurt. Porsche claims a 0-to-60-mph time of 2.7 seconds, but in reality it's more like 2.3 seconds. More impressive than its…