Nice work. I think this is probably more powerful than Supercannon II. 2400 psi vs. 100 psi is no comparison. But Supercannon II definitely beat his system in energy efficiency. His jet suffers from extreme breakup, while Supercannon II is fairly coherent for the fire hose nozzle. I could do better now, even.
The success of videos like this (over 1 million views in 2 days!) suggests to me that there's still a lot of interest in water guns, and we're just not capturing it here at WWN.
Anyhow, there are "hydraulic monitors" for mining that have jets like 3 inches in diameter, so this is definitely not the largest water blaster of any variety.