2 x 25 lit is max size now, upgrade to bigger may be possible but for sure
need extra development time. Pulse of bigger volume have impact on
airframe too.
It may be better to use second standard 2 x 25 lit canon stacked (4 together)
One pulse per second is nice capability.....3000 liters of major water fluid can
be used than within 120 sec also combined with foam agent too....
See bellow demo of SAFIRE foam used in aviation fire.....