RE: Speaker Sizes
the woofer sizes are 5x7/6x8's all around, with 4 tweeters, two in the front on top of the doors, two in the back right next to the woofer.
6.5" rounds are a fairly easy replacement, and some folks have 7 inch woofers there as well. I have heard of one or two that put 10 inch woofers in the doors, but that's a bit extreme. It all depends on how much cutting you want to do.