An injector bung could be welded above each port, that would not be hard. Drill a hole, weld the bung, no AUX spacer needed. The problem I see with the AUX injectors is that they are batch fired. I'm not a tuner or a computer nerd but how hard would it be to tap into the stock injector harness and pair up the injectors. I'm sure that resistance or ohms or some other electrical engineering black magic would come into play but hey something to think about.