Stock speakers are good enough, just need an amp. Check out the Alpine Power Pack. You'll notice cleaner highs and bass than just upgrading the speakers.
Whats your deck RMS? You have an amp that can push those kicker speakers over their peak RMS?Trust me, you're guna want new speakers. After a while stock gets pretty old. I got some Zstats installed and im already tired of them. I got some Kicker KS speakers on my watch list on ebay. 190 watts per speaker. Can't wait til the money's right!