Hi, I put Alpine SXE 5725S 5" x 7" two way co axials in the rear of mine, currently some on Ebay for £44.95 - I seem to remember reusing the plastic frames of the original speakers but it was a pretty straight forwards swap, need to change connector terminals too.
I also fitted JBL Stage 602E 16.5 cm two way co axials to the front, there are currently similar listed for around £50 you can refit the original grills or use the ones that came with the speakers with these, I did the later as the originals weren't in the best shape.
Sounds loads better, I kept the original tweeters in the screen pillars.