i have an 06 gt and just had the v3 put on at mustang magic.........it def. makes a difference in power.......figure stock gt on dyno makes 285 horsepower somewhere around there and torque is around that as well......after the dyno with the V3 the car made 418 horsepower and 380 torque.............but then again i also have an automatic (but atleast its convertible)....with manual you will gain a bit more power