I don't think there has been much, if any research on this subject simply because nobody with a GA16DE has had a need for one yet. Apparently our stock set up is the best until you start going crazy with mods, so it's just not necessary I guess.
i guess I really should have asked this question for the my possible up-comming SE-R classic project, I forgot that Vermont(where my car is registered) wants OBD II compiance for 96 and up cars for state inspection. So a stand-alone is out of the question for my XE. Anyway I think Its still an interesting idea, keep the post comming for other guys here.