i have been looking at mk7 axles for a project of mine, best ratio i found was 3.31, that would almost half your revs at a given speed, way better for motorway use, if i was changing ratios i would swap the whole axle, its the easiest option i would have said, they do a 3.55 as well, depending on load carrying you may net have the power to pull the 3.31, what model is the transit, guessing a 330 or 350 as its rwd, single or twin wheel