from what i heard, in addition to a removed speed limiter and fan point for 180 stat.
you can get firmer shift, and its still reliable, theres also skip downshift(going from 4th to 2nd and 3rd to 1st)
better air/fuel mix.
theres more options you can have but thats all i know(according to your mod)
i plan purchasing a pcm myself ,and doin 1.9 rocker next year, to go with my 3.25 pulley(not installed, 3.4 right now)
foghorn or rogue will give you more accurate options for the PCM, they know there stuff
or anyone else who have a PCM.