Only the exhaust will give you any increase in torque at the Flywheel.
The gearing change will give you more tractive force, which will make it feel like it has a lot more power.
I'm contemplating a change from 4/11 to 4.83 in my Rover for the same reason.
Easier and cheaper to get more power (torque) on the ground with gears than playing with the engine. Been there and done that with the UZ and didn't like the fuel economy of 45l/100klm!
I would expect an improvement in economy as the throttle opening won't be as large to keep it rolling.
Mine only weighs 1850kg and runs 35's.
45/ 100 OMG
![Eek! :eek: :eek:](https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f631.png)
The gearing will have a direct result in + torque as it is easier to run making it give better performance.. and spin off is better economy..