Thats bollocks that the ratios are out for an XE, when infact its slightly geard for less in gears 1, 2, 3, 4 and 5 at the same RPM on the F28 compared to the widest F20 they did.

Just won't have much joy accelrating much in sixth, but its an excellent economy gear! Not worth the cost and hassle, and you would need to find a box and a new clutch. Then mount and fit it. Costly excercise.