Aftermarket EFI on a Magnum- your experience??

What is your planned use? If ypur using it for Daily driver and do a lot of driving go with the port injection with sequential. That would look like the Pro-flo4 or stock with a megasquirt. Would be for that little extra mpg.
I have heard good things about the holley sniper kits as well. If you go that route hit up @Johnny Mac as he helps the guys out.