Little if any. Your cooking temp is your cooking temp no matter how many are on there. Putting the additional cold meat on may initially cool things down a bit, but not enough to make a difference in my experience. What temp are you cooking at to get an eight pound butt done in eight hours? Seven to eight pound butts take me about 14 hours at 225-250 unwrapped.

Mike

Know fat, know flavor. No fat, no flavor.

I tried going vegan, but then realized it was a big missed steak.