If you are interested in Sound Quality over loudness (SPL), there is an objective way to tune. Tune so that the car reproduces acoustical performances as realistically as possible in terms of tonal balance, depth, and ambience.

Not as easy as it sounds. But there are tuners that come close but at a price. This involves not only adjsutments in a system but the careful choice of equipent and mounting locations.

So in defining correct tuning, the question will be for who?

In determining what the final setup will be, ask yourself, who do you want to please? Sometimes, it's not always yourself.