Dan, here's a link to a site that does a pretty good job of describing the process. http://harrymoto.com/MX/maps.html

While this particular one is aimed at motorcycle guys, the concepts are the same. Some interesting info on the spreadsheet attachment.

Here's another link for the Holley Commander 950 controller. http://www.holley.com/HiOctn/ProdLin...A/534-144.html

The wiring harness size will depend on how many of the sensors you choose to use. They look pretty ugly when lying in a pile, but with some effort a lot of it can be routed in such a way as to not be too apparent. Remember how clean Trepanier made that engine compartment on the Ebay mustang look?

Most of the aftermarket suppliers of ECM's will include the software and instructions so that you can "play" with the mapping on your laptop. Or if you recall, the Mooneyes set up came with a "simple", dedicated, controller box with an LED readout panel.

Don, I'm not sure where you wanted to go with your original question. Were you fishing for info, say like the differences between mechanical systems (like the old Chev and Pontiac Rochester units) vs electronic? Or how much effort goes into assembling a complete system?