I smoked 6 slabs in my No. 1 this weekend. Absolutely packed full, about 18-20 total pounds. Now having done it, I would probably agree that was overloaded. But worked OK in my book (one rib rack and one regular grill shelf, 2 half slabs on top of the ribs in the rib rack). I learned that 6 slabs will produce enough grease to fill the bottom grease pan almost brim full. No spills, but oh so close.