Wait, Thermobaric ammo? Did IO really give the Artillery Cannons their first alternative ammo? (Standard artillery ammo options are not available to Artillery Cannons.) Mostly wondering because the damage values seem appropriate to artillery pieces, not Artillery Cannons.
EDIT Huh, yup, no doubt. They even got values in table section! Wow...
Anyway, amusing variant, though unfortunately Thumper Cannons kinda suck. Though i have admit they probably wipe out infantry nicely, or clear minefields or other stuff like that.
EDIT Make that "Thumper Cannons suck, except when loaded with Thermobarics".