It would appear that some have an incorrect understanding of gear ratios. So FYI here's how it works:
for example, old mate has a 3:1 first gear a 2.5:1 2nd, a 2:1 3rd, and a 3.9:1 diff ratio.
He feels that 1st gear is "too low" (ie car hauls a55 in 1st but bogs down when it hits 2nd)
He could change the diff ratio to a higher 4.11, (higher number= lower ratio), this would give the impression of the gears being closer together, but at the same time rather than fixing the problem he is just masking it. with the downfall being less overall top end.(more torque would fix it properly though, as Adam_RSX said.)
The solution is to lower the ratio of 1st gear,(raise the number) to maybe 2.8:1
He is raising 1st by lowering the ratio, bringing 1st closer to 2nd.
Higher the number, lower the ratio.......
PS if you all already knew this then maybe i just got confused along the thread...
Jason