Not to take over your thread but since you guys are talking about Alfa? If I have halogen tail lights and want to switch to the sport leds, I know jj at retro sells the reisitor packs but wouldn’t using Alfa with an adapter be enough?
If you have AlfaOBD you don't need resistors for anything. That being said, i just did LED Spyder taillights and they have built in resistors. So if what you are buying is already built to be "error free" without external resistors their is no need to tear the built in resistors out. It's just the bulky external ones that aren't worth keeping.