My Pioneer speakers were $75 a pair so you don't have to spend that much if you're going for only 2 speakers. I'd changed all four speakers to balance it out, but that's just me.

 

I thought the stock speakers really sounded lousy. I did a set of Phoenix Gold RSD6.5CS in the front (Seperate woofer and tweeter, $79 on ebay) and added a small amplifier to power them. I also used some old 6" speakers the rear.

I imagine you you don't want external amplifier. Phoenix Gold makes a nice coaxial speakers well. The factory front speaker is 5 1/4" however when you remove it the opening will fit a 6.5" speaker. I have to make a 1/2" spacer so my window would roll all the way down. The rear 6" speakers fit right in.

 

If you want to run the speakers off the internal amp, then you should buy some inexpensive speakers that can handle close to 20 watts RMS rating of your headunit.

following prices are from crutchfield, shop around and you'll find them for cheaper
Kenwood KFC-1362S - $50 a pair
Kenwood KFC-1382ie - $70 a pair
Pioneer TS-G1342R - $50 a pair
Pioneer TS-A1302C - $150 a pair but they're components and made from better quality materials

 

thanks for the suggestions so far, i'll look those up. I will definitely do without an external amplifier.

 

All you have to do is get the size of your stock speakers and just up grade to what ever brand speakers you enjoy and thats all you need

 

i spent 100 for headunit Sony,
100 for new flat design Sony speakers front installed
and 125 for rear speakers to match. clean clear audio system and lil remote. haha

 

My speaker selection and install are detailed in this post