I suggest getting the 5.25 speaker adapter ring from Jim Clayton. He is on this forum. It is a big improvement over the stock 4" and open up a wider variety of speaker choices. I am using his ring and running JL Audio VR525-CXi Front and Rear and enjoying them very much. There are quite a few others using the same set up here.
If you decide to go with the JL's look on ebay I got mine there at a great price.
If you decide to go with the JL's look on ebay I got mine there at a great price.