That is one BIG bunch of racks. I have done six at one time--man, was that grate crowded! Used a rib rack for four of them, then managed to squeeze the other two around the rack. Yes, the cooking time was longer. Been a couple years back, but think it took close to an hour more to get them so they were OK. I prefer to have them cooked a bit longer, but was getting hounded to feed people. SO, went ahead and took them off. They were OK, but like I said, prefer them a bit more done--to the point where there is just a bit of resistance when you bite into them.