on my car at 29-30lbs of fuel @ 3000 rpms cruising the AFR is 13.7 to 1.
bump up the fuel pressure to 35-36 lbs @ the same speed the AFR is .....13.1 to 1.
So in this case it don't adjust it that much but for fine tuning its fine. It seemed to change it across the board including WOT that much.
These are just cleaned and tested 2.0L injectors too.