Standalone management will come with its own wiring harness. You will need EFI pedal (which consists of undoing 2 bolts), throttle cable, injectors, coil pack, ignition leads, sensors, and depending on where you get your trigger sensor from you will either need to drill your block to accommodate the efi cps bracket with an efi flywheel; this method is getting a lot harder to do as the fiesta cps bracket is near impossible to find. You could alternatively use a trigger wheel and keep your mfi flywheel. You could use the efi inlet but you would either need a conversion plate from efi to mfi to retain the mfi head or just swap the head for an efi one. As for old mfi loom if you want to keep it you could just leave all the connections as they are but if you are doing it properly then the correct way to do it is to cut all the mfi loom wires out and merge the new standalone management loom by the end of it having a nice neat loom. Easier said than done, but a its definitely worth doing it. Granted there's nothing wrong with MFI when maintained correctly but for the amount of hassle you can get when it comes to problems with mfi I would seriously recommend the conversion. Its not a simple conversion but once you get your head around the whole process it is very straightforward.