I agree with the earlier posts mentioning "tradeoffs".
I once put a chip in a Saab 9000 Turbo. It really boosted the power, by allowing turbo over-boost which the basic system did not. I recall it allowed full boost for 15 seconds where the stock system only allowed momentary (a second) overboost.
Power was amazing - but the tradeoff occurred after a few weeks - I blew the turbo.
What about the GForce? If it leans out the mixture, you will, at best, get the check engine light, because lean mixtures burn hotter which increase pollution. Further, they can create hot spots in the engine and burn valves and pistons if left uncorrected.
If under load it increases fuel, it creates more pollution as well, and can, if rich enough, allow unburned fuel to seep down the sides of the pistons and contaminate the oil. With today's longer oil change intervals, this can lead to excess engine wear, which you will not notice for a few years, but is uncorrectable.
Finally, the electronics in these vehicles are extremely sophisticated. Voltages must be maintained very accurately, and the cars contain power conditioning circuits to do this. Anyone who hooks into the main data buss on the car risks voltage spikes and outright destruction of sensitive components.
If your manufacturer doesn't allow the upgrade (all of them have approved after-market parts which have been tested), then stay away. If you have a 15 year old beater and you want to experiment, then try it out and if it trashes the ECU, junk the car.