I've just this passed weekend got my megasquirt'ed 440 running, idling, and am in the process of accel tuning. It does everything I could ever want and more. Knock sense/retardation, controls timing (something not all efi systems can accomplish), multiple outputs and inputs (independent EGT probes, cooling e-fan control, etc), flex fuel options, boost control, NO2 control, launch control, and the list goes on.

If you've got the time and really want to understand the exacting sciences behind fuel injection, check out megasquirt. If you just want something to come in a box and slap it on and have it run OK, give something else a try.