advice from ICE guru's

[alfamale]

I have some sub woofer speakers laying around in the garage and wanted to add them to the storage bins behind the seats, i would rather not install a seperate Amp but run them off the standard head unit, is this possible? how do i wire them so one speaker plays the low notes from both channels or is it better (simpler)to have one for each channel. will i need a cross over or is that just for use with an amp install
as you can guess i am no expert but i know enough to know i need help