I tested Revision #3 on 3) BUFORDS this weekend. Drum #1 had 6) coiled large baby backs on the top grate, Drum #2 had regular sized baby backs on the top grate and Drum #3 had two racks (10 lbs) of wings.
First, the success story;
Drum #2 had Rev #3 diffuser placed at about the second ring on the drum. Six coiled regular sized baby backs were placed on the top rack of the cone top drum. Fire started and within 45 minutes, the drum had settled in at 225 degrees and held 225-240 throughout the entire cook with only a few tweaks for regulation.
Prior to the cook, I placed a digital probe (Maverick) about 6 inches above the diffuser to monitor the center heat. The digital center probe read 225-240 and the two outside edge analog gauges (2.5" probes) read with 1 and 10 degrees of the digital throughout the entire cook! Definitely a success!
Drum #1 had diffuser revision #3 but had the largest ribs on the top shelf. There was very little space between them when placed on the rack. Diffuser was placed about the second ring on the drum and the digital probe placed in the same spot. This cook took a little more regulation and we saw 20 degree temperature differences between the analog and digital thermos. The diffuser #3 is not a good fit for meat that is packed heavily on the grates which restricts the exhaust. And, number two, there were three of us tweaking it throughout the day and we didn't communicate our adjsutments between us. Too many cooks in the kitchen.
Drum #3, diffuser #3 had two racks packed full of chicken wings and the digital probe placed a few inches above the diffuser that was about the second ring on the drum. I saw about a 20 degree difference between the digital and the analog gauges on this cook as well. I also encountered another problem. I was unable to get the drum up to temperature. Way too much blockage by the diffuser and the two layers of chicken wings which were also tightly packed on the grates. I was able to increase the temp by openening and closing the side access door that is on the BUFORDS to get the temp up.
Overall, it looks as if the Diffuser #3 worked perfectly on Drum #2 with 6 coiled normal sized ribs. Throughout the cook, the center drum temps were within a few degrees of the side analog gauges. I'll do some more eperimenting on this design.
I would not recomend Diffuser #3 for those cooks that have tightly packed meat on one or tow greats. The diffuser, with the tightly packed meat restricts the exhaust flow through the drum causing temperature temeprature fluctuations and excessive smoking issues.
Diffuser #2 would probbaly work better since it has more vent rings cut into it.
BTW, the ribs turned out fantastic, good even bark, no charred ends, nice smoke ring, succulent! The wings turned out ok, rubbery skin, too smoky due to low exhaust ventialtion early in the cook.