I had only the tweeters + 8" midbass/midrange in the door. I think earlier ones came stock with 3-way system. Anyway, I installed 4" 2-way co-axial MTX speakers to the midrange position at the top of door and cut the wiring to the original tweeter. I have active filtering and separate amp channels for all speakers (below 150Hz to midbass and over 150Hz to coaxials). With time alignment, Im very happy how it sounds now and sound stage is focused very nicely to the center of top dash.
I picked the MTX speakers for 2 reasons, they were the shallowest I could find and they also won one test in a Finnish carsound magazine. They were also very cheap to buy. Im sure there are a lot better speakers out there, but they tend to be too deep for the install. Even with these, I run into sun issues with clearance.
This is just one more option how the front speakers can be configured.