I've been comparing gear ratio options. and one of the numbers i've been looking at is the difference between one gear and the next. easy way to compare these is to divide the lower ratio by the higher one. you'll notice that with almost all stock boxes, the jump is steadily increasing. each of the 4 gear ratios being about 5% closer than the last. putting a wrx .738 5th gear in with a 1.066 4th makes the 4-5 gap about 5% wider than the 3-4 than the stock .972 4th.
when I get home, I'll post up my numbers.