6A is tops for the led before the bond wires blow on the newer XML-2 LEDs. With spring bypasses and a top 4.2V cell this is possible but only briefly. Keep in mind the more current you pull from the battery the faster the voltage will drop and fall out of regulation(start dimming). This post by Djozz should clue you in to what you’re looking for. 12-13 chips with good heat sinking and low resistance mods(spring bypasses etc) is doable.