Need Tips on Smoking Boston Butt

I took a closer look at how the dome lid fits onto the middle section of the smoker yesterday. The fit was awful as there were several large gaps between the edge of the lid and the middle section when it was set on the smoker. I think I am losing a large percentage of my smoke through these gaps. I am going to close these with aluminum foil during the next smoke and see if that helps. I'm also going to use more chunks of wood since I have been able to raise the water pan a little bit.

Thanks again for the help, especially the recipe.