I did not sleeve it, but used an 1/8" gap to make sure it was 100% through. All the welds on the frame are like this and have been through hell without any problems. If I plate it it will not flex the same and may cause cracks next to the plate. I did not grind the welds to keep from weakening them. I may put a diamond plate over them, but feel this may just be over kill. The frame is already about 3 times stronger than stock.
All the cage joints are sleeved.