30-80mph is what the OP said, the Subaru would not have been in 4th gear. Likely 2nd, possibly 3rd if the driver was ignoramus, but even in 3rd the car would soon hit 3k rpms and fly past the Fiesta. I've owned both cars, overboost or not, weight differences aside, even if a monkey were driving the Subaru, there aren't many variables in a straight line race, the STi is fast, the FiST is slow especially in stock form, bottom line folks.