According to www.svt.ford.com
The GT500 is 500hp, 480 lb/tq, and 3,920lbs.
According to www.bmwusa.com
The 335i coupe is 3571 lbs for the manual and 3582 lbs for the auto.
That puts the GT500 only 340 to 350 lbs heaveir than the 335i coupe, not 500 lbs. Again, according to the sites.