CD Player

I want to know the specs (mainly wattage) of the CD player that came with my 2000 Altima GXE. I put four new 3-way SONY speakers but the sound isn't yet as good as my other car which is a Camry. Can you please give me the specs.
Also any hints on the best speakers and cd player combinations? I don't wanna put amplifiers. Use the original wiring. I am also thinking of putting in tweeters.
Thanks.

I'd go with Infinity Components... With an Pioneer Cd Player... I have a Sony Cd Player and the Infinity Reference Component... for both front and rear. My system has no amplifiers but it puts out Crisp sounds.

-G-