Before/After tune results?
you could do a scan and notice that you are way rich or way lean in which case you will noticably benefit from recalibrating the maf and adjusting the fueling. Maybe your car has an air restriction you don't know about, or has better air flow than other cars.
My point is, it varies from car to car, and is one of the reasons why I don't like generic mail order tunes.
So in short- it depends lol



