You need to monitor your Air/Fuel ratios to see what you are truly doing. You can control AFR's in the closed loop range by playing with the O2 sensors, and never touch the MAF sensor. You only need to play with the upstream sensors, the downstream only tells the PCM how well the cats are doing. Only by changing the MAF sensor feed to the PCM can you change the AFR's in wide open throttle range.

Skewing MAF or MAP sensor voltages in a non forced induction car is pretty easy to do, either adding or taking away some of the fuel. It tricks the computer into thinking the car is under more or less load than it is. This puts the PCM into a richer or leaner fuel table within it's own programming.

Not so easy or the best solution for forced induction vehicles.

Mr MoPar