I am installing the ez 12 circuit with mini fuse box. I added a fuel pump and the choke circuit is spared. I did quite a bit of modifying to fit a lot of relays behind the dash because I don't want to overheat the combo switch. My experience with the kit is fine so far. I think wiring is easy as long as you keep everything well documented and tidy. I drew a wiring diagram since I want to be able to open the dash in the future and know what goes where. My car is a 71 240z with L28, MSD ignition, gm alternator, kill switch. 12 circuit is just enough to get the job done, BUT if you ask me to do it again I would not buy the kit and make a harness myself and make it perfect. Oh, also the fuse box doesn't fit in the original place.