Also after reading back over some of the other earlier comments, I found that adding the stack pretty much eliminated any of the remaining wisps of smoke that came from around the rim of the lid. Better draft I suppose.
I will definitely try out the "1 cap off- see where it lands" experiment. I think it would be good to know "terminal velocity" with one open cap. I agree that it would be good to know a "baseline" of sorts.
Silver Smoker with all the typical mods, UDS, 18.5 Weber OTS, Smokey Joe