Replaced the 6.5 components up front, and was recommended coaxial 6.5's for the rear doors. I was not happy with the sound as it was all firing downwards and created too much of a front stage from the upfront speakers other wise. So I swapped them out for another component set.

Popped off and removed the door panel, used a compact palm router to buzz open a hole for the tweeter (be sure to remove the white cotton foam) and voila. Took about an hourish per door

Definitely balances out the sound with a nice surround effect. Tweets are swivel mount, so can adjust angles.

They are running off the stock amp setup and all sounds very decent, big improvement over the flimsy yellow stock speakers