Yes, pretty much every diesel has that sort of thing going on.

Better response from standstill - assumed this was down to amplifying the signal seen from the same movement of the accelerator pedal. As you say, they aren't increasing how much exhaust gas is being made.

I have had remapped cars for years, both petrol and turbo diesel. I am shocked that anyone would shell out £70k + on a car and then plug a £200 box in to make it perform better

I spent £600 doing the D3 but that included a specific map and an expert doing it. My D3 went from 190bhp to 245bhp with a shift to 680Nm approx. Perfect for my driving and towing. People suggested at the time I should use a 'blue fin' box that delivered 280bhp to a D3 and was £140 of fleabay. Plug onto the diesel rail and thats it....

When something appears to good...... Is this where I put the car details and a bit about myself ?........

My suspicions too

Just responding to the lag from junctions etc. One thing that JLR have done with gearbox mapping is coming to a halt in second gear and pulling away in same. This means that you will not get rapid acceleration from rest unless you really push the pedal then the box goes for 1st and hold on. This feels like lag too. It's done for economy reasons I think.

But I still cannot see how a tuning box generates instant response from standstill by mapping other than by increasing the idle fuelling at expense of economy? Power=fuel+air. Fuel can be done by remap/plugin tomfoolery, air needs a spooling turbo and good airflow. Is the turbo a variable vane unit with electronic control that can also be fooled? Or have I lost the plot and they have rewritten the rules of combustion?

I'm suspicious of the cheap performance claims. 2019 D5 HSE Lux SDV6 Indus
55 D3 SE
98 MX5 1.8 RS
gone 17 older variants of FFRR

It puts in more fuel, and at a higher pressure, which helps with throttle response