Without going all crazy with amps, subs and stuff and since my Wave is a lease (for now, don't know if I want to buy it) I have a little question to the audiophiles here.

If I were to replace the speakers in the doors and in the back with:

6 1/2" 50W RMS for the doors and
4x6" 40W RMS in the back

Would I need an amp? These speakers are really cheap and my main idea is that the "Real RMS value" is much lower....

Still would I need an amp? They say that they are great replacement speakers on the box these are two way speakers also. I just want to improve the sound a little, not really make it louder.