How much Rms wattage door speakers will I need to be able to withstand my 450w kenwood car amp?

I just recently put a 450w amp, 2 12inch subs, and 2 rear 800w speakers in my car. My problem is, is that I need to find 2 door speakers with enough RMS that can handle the wattage of my amp, my stock one's.. needless to say.. probably won't last much longer. lol