The thread on the downdraft has me wondering... If you were to use a valve like the downdrafts are using between the main smoker and the cold box would it help with temps?

Good question.  I think the point of the downdraft hood is to get smoke to exit lower.  The smoker box wouldn't help with that.

No but using a rotating valve (not sure what the rotating damper/valve thing is called) between the smoker and the cold box without the downdraft hood...that is what I mean. Would it allow you to fine tune the heat entering the cold box.

True but not sure how it would affect the performance of the smoker itself.

Fair enough. I guess a person could rig up a pretty simple test run by just blocking some of the airflow between main box and cold box to see how it effects the temps. Maybe once I get the upgraded controller, it will give me an extra ambient probe.