Here this may help a bit.
http://www.the12volt.com/caraudio/boxcalcs.asp
Dont worry about the rms and peak of your subs. Just get the best and biggest amp or amps you can afford. If the subs are only rated for 400 watts rms, and you put an 800rms amp on it. Its not problem. Just turn the gain on the amp ALL THE WAY DOWN and it will clear clean bass as long as you have them hookedup. I know someone gonna argue this with me. But I been runnin 2 Eclipse 10"s that were new in 98. 200rms each and I have had nothing less than 400rms on them since they were new. They still sound great. Just dont turn the amp up, and dont over kill . Keep the loud button on the head unit off and the bass down.