I cook with all exhaust holes open on top and 90% of the time I have 2 air intakes open at the bottom.
I have 4 air intakes around the bottom of the drum. 3- 3/4" holes with pipe nipples and 1- 3/4" ball valve.
The drum has been working great for years.
My new BPS drum has the 8 hole wheel exhaust.
and two strips of intake holes around the bottom..just slide to open as many air holes as needed.
Love this BPS drum too.. works great!