Motor Mounts,
Motor Trend Reported it couple times
5th paragraph down
2010 Ford F-150 SVT Raptor 6.2 First Drive - Motor Trend
11th paragraph down
Flight of the New SVT Raptor SuperCrew - Motor Trend
During the Raptor sema debut in 08, I remember an interview with Jamal Hameedi that talked about the motor mounts being strengthened. I looked for it but its like finding a needle in a hay stack. I know other media sources have repeated the same thing Motor Trend did.
Also, from what I can tell looking up the parts, the part numbers for motor mounts are different between regular 6.2 f150 and the 6.2 Raptor (at least for the year 2011).
The Raptor front end body parts might be and probably are heavier than a regular F150. But just looking at the Raptor, from what I recall, Ford claimed they left the Raptor bedsides sheet metal on purpose to add weight to the rear of the truck for better balance.