Im not saying making more ultimate power will not use more fuel, of course it will, on boost under load, no doubt about that whatsoever. A T4 car at 32psi on 83s will return 7-10mpg under hard load if you are lucky.because it flows more air, so in turn requires far more fuel to maintain a safe AFR. That point is not in question.

But the bigger turbo powered cars will spend more time off boost, thats my point.

it comes down to usage. so its not a simple as "if you fit bigger injectors or a bigger Turbo it will use more fuel" because that is not true, it depends on many other variables.

I have used all manner of spec Cosworth cars for many years on daily basis, completed 75k miles in 3 years in my last one.
And if i were to use a T3 powered car today for my trip to work there are a few places i could see some boost, but swap to a T4, no chance i doubt i would ever see positive pressure on a daily basis. And thats my point. It comes down to usage.

Also the smaller turbo exhaust housings are a massive restriction in the exhaust, by fitting larger housings the engine becomes far more efficient.

As for stage 1 economy, well its pretty easy to improve over the std map, it was far from perfect, and there are many areas for improvment, not just in the fuel map.

If you 255 the top line of the fuel map, you can still go lean on a T3, as the turbo can outflow the std injectors. so you cannot allow the turbo to do its thing at high rpm,the boost has to be capped. which is why i advise 803 greens, as they outflow the T3 which is always by far the safest option.

You get a similar situation running 803 greens on a T34, where the turbo can outflow the injectors, so boost has to be capped. In that case with a T34 i would advise 55lb Siemens, so the turbo can be used flat out.