Or something that simply SOUNDS GOOD. That's all you need.
There are only a few shops that I hold in high regard: The Autophile (Peter Lufrano), Sound Innovations (Ernie I-can't-think-of-his-last-name-right-now), Sounds Good Stereo (Isaac Goren), Hybrid-Audio (Scott Buwalda) to just name a few and ALL of the owner's cars don't have a single drop of fiberglass resin in their cars (with the exception being kickpods).
Why?
Because they don't need to.
Customers, at least the intelligent ones, step foot inside a car audio shop looking for what sounds the BEST. The owner's car serves as the PERFECT/BEST selling tool as it provide a benchmark for what sounds GOOD.
It's very easy to sell a system + installation that maintains functionality, flexibility, and above all, SOUNDS GREAT.
It's almost IMPOSSIBLE to sell a 10,000 dollar fiberglass job that's poorly tuned, carelessly wired, takes up the whole **** trunk, and sounds like the ****** lips on your grandma grinding together.
Just my 2 cents.