The full bridge. Same antenna feedback, a more robust (and admittedly shoot-through-prone) gate drive, IRFP260s run right at their edge on 170 V DC, and 21 in sparks at about 1600 W. “I am sure that having a driver that is always in tune helps a great amount!”
Schematics and photos
SSTC-2 · 100 0085 
SSTC-2 · 100 0112 
SSTC-2 · 101 0141 
SSTC-2 · 2SSTC01 
SSTC-2 · 2SSTC04 
SSTC-2 · SSTC2 01 
SSTC-2 · SSTC2 02 
SSTC-2 · SSTC2 03
Sources
This is the card from the driver tree, written from what the builder published. Send corrections through the forum.