I don't have any hard facts, but i was just talking and crawling under another 80 series this summer that has the exact same lift as mine (slee 4inch) and we were discussing links. He had custom lower links and custom panhards I asked him how he knew what length to make them and he told me that he had a friend who worked at a high end tuner/fab/race shop in CA and that he kind of wanted to set up the suspension as a fun exercise. So i measured his links compared to my stock links and they were literally only 1/2inch longer than stock IIRC. I actually have the measurements written down, but i was surprised that it wasn't much. I think the lower links were like ½ inch longer and the panhards were ¼ inch longer.