Here we go...
Above: setting up the 4" gap

Above: 4" corona discharge

Above: 4" single discharge

Above: 4" more corona

Above: 4" multiple arcs!

Above: setting up for 4.5" gap

Above: 4.5" corona. Tranformer blew out but I did get a few
arcs.
At this point my transformer pretty much gave up. There was intense arcing from the grommet where one lead exits the steel case. I'll try some heatshrink and silicone junk on there so see if it can be saved.