you should look at the gear ratios, in the 5 speed 4th is 1 to 1, in the 8 speed 7 is 1to1, the later box may have 8 gears but thats only to fil in the spaces between the 5 speed to make changing even smother, the manual 6th gear is a lower gear than the 5 speed autos 5th so i need more revs...