Using a 2 1/4" exhaust pipe (bent @ 90*) for the intake, running wide open, with a home made (redneck mod) coal basket, I got temps between 350* & 450* using Rancher lump today. Temps were measured using a dial - type meat thermo with a 6 inch stem. I just stuck it in the exhaust vent (3" pipe, about 16" to 18" tall) like you do to measure the dome temp of the WSM. The real temps may have been higher, but I won't know until I get a reading with a mounted thermo or install the grates & use the ET-73.
The next steps will be another
burn to get the paint off of the inside (how many of these will I have to do?), installing the grates, cutting the ring off of the free
22 1/2" kettle that I scored today, building the ash-pan & the slide covers for the intake & exhaust tubes.
I keep doing a little at a time & keep thinking of more things to make / add to this "little project"