The gauge doesnt adjust anything, it's only there to monitor the air to fuel ratio. A very important gauge with modded cars.
Stoich is 14.7, when it's in the exhaust with the vehicle running it will bounce around 14.7ish all the time at idle and under normal load. When you step on it, it will creep lower and lower to a some numbers. Likely you want to see 10.5 to 11.5ish for a boosted vehicle, that means it's running a tad rich but still sorta safe.
Read up on widebands to get more info on how they work.
