Probably you need to add a serial diode on stop signal to the original tail light and connect your hyper lites before, directly on stop signal from switches. In this way you have to cut the original yellow/green wire and so it will be not origina anymore. For my point of view is not a problem. The main thing is to do a good and reliable job.Thanks Scott - I think I also need to install a diode or two? - to get it to flash? Do I use one or two diodes as there are two lines separate from ground. *Positaps thanks! Here is what it looks like attached now. Lighting up but not flashing as it should. I believe I need to add a Diode, but to which or both wires is my understanding? I did use quick connectors of a flat kind not as good as posi-taps.
For the diode is better use a schottky type diode as a 1N5822 or a 20SQ045.