For the fronts, all you have to do is drill new holes. (Unless they are really deep, then you'll need a spacer.)
For the rears, I had to grind away some of the door where the bracing on the speaker was. Some people instead cut/ground the door handle brace, but i wanted to leave that.
Overall, not a bad job. I have pics of the door panels off if you'd like to see them.
