Front brakes improvement

In a Jimny, decent high temperature pads to avoid crystallization and good discs, coupled with DOT 5.1 and braided lines to prevent boiling and better tolerate the heat should make a big difference... if this is not enough yeah, a conversion with ventilated discs and more capable calipers, but that would require a new pump to do the things right, since the stock one possibly won´t cope well.  As mentioned  before, the drums in the rear are not such a big deal, since 70% of the braking happens on the front. Discs can get really hot, but fading and/or crystallization should not happen so easily with all the above. The only thing to keep in mind if discs get too hot would be to drive slowly for 5 minutes while being super light on the brakes to let them cool down in a uniform way. Otherwise,  they will bend due to non uniform cooling.

I did not have any problem with the brakes of my Gen 4, particularly considering how slow is the little guy and how much you can use the engine and gear box to control the speed. That said, when it comes to change brake fluid and pads I will go for braided lines, DOT5.1 and soft pads just because. Huge tyres will always have more momentum, though, so an upgrade could be justified in that case.