No it doesn't change airflow into the motor, but it's simple physics, it's easier for the engine to move with less weight than with more weight. This applies to off the dyno as that's where stuff matters and the car actually moves. Your car can dyno 900000 hp but on the road it could only be 4 hp.
That tune right there is an 03 dropped to 2835 lbs with 450 lbs of stuff, me, and my tuner in it. = 298 whp