What is Zagato magic? Well, in the case of this 2003 Aston Martin DB7 Zagato, it translates to more than 440 horsepower from the 5.9-liter V12, eight fewer inches in overall length and a weight savings somewhere around 200 pounds. Add in styling cues like the double-bubble roof line--a Zagato signature--and a completely reworked rear end treatment and you get one …