I have. My brother has a complete custom sound system in his Lancer, I really only like how the bass is. That's about it.
Are the 6.5'' speakers in the doors woofers, full range or mid range?
Also, just because someone has a full aftermarket system doesn't mean its any good. There are plenty of very bad habits that people have with entry level aftermarket sound. I was as guilty as anyone else, but I've been learning.