Gtech just takes the boost limiter off 1st and 2nd gear
It doesn't "just" remove the boost limiter in 1st and 2nd gear. It increases boost in all gears and also modifies the overboost, fuelling and ignition timing maps.
Almost every coupe tuning chip removes the boost limiter , as does using a manual bleed valve or (almost) any electronic boost controller. So if you have a particular desire to be able to floor it in 1st and 2nd without spinning the wheels in the wet then you'll need to be running with no performance mods at all and also with some incredibly good tyres.