Well, There's a 21 pounder (pre trim) on the grill right now. I did a heavy S&P on it before placing it out there last night. The concern is, with such a large brisket, as you get to the middle, away from the bark, there will just be the flavor of meat and fat. Never cooked one this big and yes thinking about it now - injection would have been the way to go. We are WAY past that point, so any favorite sauces/gravies you can share to go with the brisket?