A full schematic would be ideal. But the FET PN would go a long way as that is a major component. If you look at the Jag's power path, it has a 1mOhm resistor and two legs of the Hbridge in series with the motor.
The Jag FET spec says:
MOSFET N-CH, TO-220 40V/60V 80A
However it lists 3 FET PNs
IRFB3206PBF: 60V 120A 2.4/3 mOhm (typ/max)
FDP038AN06A0: 60V 80A 3.8 mOhm
FDP050AN06A0: 60V 80A 5 mOhm
We then have an effective series resistance of between 3.4 and 6 mOhm between the battery and the motor, and a max I of between 160 and 240A (I guess no worries on max I).
The real limitation will come from power dissipation on the worst case 5mOhm FETs.
Eg: for 40A, each FET carries 20A.
P=I^2*R =2W
Thermal resistance from Junction to Ambient (no fans open space)= 62 C/W
Ambient T=25C
Therefore operating T= 149 C
The max Junction T is 175 C.
At 50A, Operating T = 219 C --- sizzzle!
The fan will help, but the math for that is below my age level. And clearly we've seen much higher current levels through Jags and they've survived.
(maybe Jags rarely use the 3rd PN?)
at 50A 1st PN 2.4mOhms: Op T = 118 C --- What a difference!
In the case of adding a third FET in parallel (like the Victor has), and keeping with the same FETs:
The current per FET is reduced by 33%, and the power dissipation by 56%.
This shows that Victors can handle far greater max power than Jags - unless they have very inferior FETs...