Let me hear what you think.
I'm talking component system for the front doors.

How deep can a 6.5 element be to fit in our doors?

depends on how much time you are willing to spend to get the baffle lined up at the perfect angle and spacing.

but the kick panels from q-logic, i have them in my ride with 6.5 components and its looks awesome

Well I have the q logics and I am starting to hate them because the sound quality sucks as compared to the door and you must have 6.25 unless you made some adapeters for 6.5s because I have 61/2s and had to make adapters to fit them into the q logic kick panels and for a 150 your about half from having a new speaker panels for the doors made so that you can fit all 6 1/2's in the doors and then you get the sound of a sealed enclousure. But I would go 6 1/2s because there are going to go just little lower unless you are a budget then get 5 1/4's.

didnt need an adaptor and mine are the infinity 6.5 component set