I'm not a fan of 6x9's in general and didn't want to cut up my doors. I did 6.5's in custom kicks tucked into the vent hole with a tweet high in the door (made a pod the aims the tweet). The pre-fab kicks are nice, too. It cost me about $25 to make mine.
Kick panel isn't mounted in this pic and I still need to install my speakers. Tweeter goes in the pod above the window crank.
