I have done a few test burns and without the diffuser I struggle to keep the temps below 250 at the grate and the slider on the air take only 1/8" open. With the diffuser, in place. I hold very easy around 170 with the intake 1/8" open and with it 1/2 open it holds around 220. I don't have any Qview as I wanted to play with it till I understood it's characteristics.
I added a 2in Stainless Steel stack, mig welded to the drum as my air intake with a makeshift slider over the opening to regulate the air intake. I stole the idea of the Wally World grill from Sawzall so I have the hinged top. The top of the stack is 22in above the floor and it attaches to the barrel at 2in above the bottom.
Here is a picture of my diffuser. It is 1/4 plate with machined holes in it. The metal over the top is the bottom of the grill cut out and bolted thru the holes. The plate sits exactly 2in over the top of the charcoal basket.
