We have seen a 50whp diffrence on a spraybar we made for a 350z's procharger FMIC. The guy was hesitant of spraying into motor and he liked to purge for show so we put 2 and 2 together and made a spray bar system.
I agree with Larry. Spray it into the motor and get rid of the lag. We do have a turbocharged car after all. Even a 50 shot would make a big difference for lag.
It is definitely not safer. You have no control or idea how much is actually being sucked into the motor. Like everyone has said, spray into the motor or not at all.