Did some googling for the hell of it and found some neat stuff for the SR guys.

http://www.925style.com/edittool_vb.html
This program lets you edit fuel and timing maps and some other variables, but it's in a fairly confusing dialect of Engrish. You guys may have better Engrish interpretation skills than I do, as you're a bit more focused on stuff happening on the other side of the Pacific.

http://www.boostcruising.com/silvia/eprom.asp
Here's a much less confusing write-up on how to make adjustments- I think the program is the same one as on the other page, but I haven't downloaded it to check.

http://www.sr20tuning.com/theoryandpartsrequired.html
Much more detailed write-up on rom tuning.

http://www.engineers.auckland.ac.nz/~lmoo016/
Live romulation (no swapping chips)

Finally, the source of this bounty:
http://www.google.com/search?hl=en&i...=Google+Search
AKA Google+ the first search term that popped into my head, "s13 rom edit"

Hopefully this isn't a double post, but I browse this forum pretty regularly and I haven't seen anything like it posted, so hopefully it will help you guys out.