Power Amp or Powered Sub?

hi guys

installed kicker CS component speakers in front and coaxial in back, both handle 10-100W RMS
currently installing a bose head thats 20W RMS

i'm mulling over what to do for more juice: install a kicker Key 200.4 mini amp with 50W RMS to each speaker, or kicker hideaway 8" sub

Seems a bad idea to do both, as crutchfield warns about too much current draw regarding the prius

What do you guys think?