I have 6.5" with a separate tweeter in stock locations in the front. Had to custom fab a bracket for it (easy). Used the spacers that came with the Infinitys. Did a lot of trimming within the door card. The tweeter pushes the grill a bit in the stock location. Not a big deal. Or you could trim part of the grill on the tweeter for it to fit behind it all perfectly. Every case is different.
I have 6.5" Infinity component in the back. I had to shave the tweeter that's built into the center of the speaker to clear the door. Had to trim the door card and remove a LOT of metal on the door itself with an airsaw. Mostly did this to quiet the nay sayers that you can't fit anything bigger than 4" in the back. Again, used everything that came with my speakers.
"We live for a good time, not a long time."
RIP Colin McRae