I'm not an expert. I've installed a P1900/Mac mini one time.
The Carnetix PSU w/ the MacPac cable kit is ridiculously easy to install.
We did not do the resistor mod, but I believe this allows the Carnetic to sleep and resume normally.
Without doing that, the owner has to press the sleep (or power) button on the Mac after ignition to get it to come on.
I believe this resistor mod is the solution for this user. I would ask people just to be certain.