Had my 2012 D-Max remapped in 2020. Cost $1250. Was it worth it? Yes I think so, much more grunt down low, ran great with the van on.
Better fuel consumption but because of the extra grunt I tend to drive it a bit hard so no savings on fuel.
On the down side, my brother got his Toyota 70 remapped at the same time and was strongly advised to replace his clutch with a heavy duty clutch as the standard clutch on the 70's wouldn't handle the extra power. I asked about the D-Max and was advised that they hadn't had any problems in the past. In 2022 I had to replace my clutch. Now I'm not sure if it was due to the remap or just normal wear & tear. Just over 100,000 ks.
Side Note: Brothers mate who also remapped his 70 poo hooed the clutch advise and 3 months later was off to SA and only got into Vic when his clutch failed.
Only thing that you might consider is that the fact that you will save a bit
of petrol is due to the fact that the extra torque produced by the engine
means that the gearbox will tend to run in a higher gear at times - feels good
but the higher gear is under undesigned strain.
Particularly heavy on the gearbox when towing because the box automatically
selects a higher gear instead of spinning more lightly in a lower gear.
On a long run on level roads typically you might look forward to a 10%
fuel saving - in the hills where you will thump it a bit more you likely will
use more fuel but climb faster because you won't be able to help yourself
from leaning on it.
I have had Steinbauer on all my (many) vehicles for as long as I can remember.