that bass tube on the rear phatta looks dangerous. it should be PROPERLY tied down.
crisp system with bass.. hmmm u have two options. with subwoofer or without subwoofer.
with subwoofer u will have to put the box on the rear seat which means 1 less seat for someone to sit. for speakers, front, get components. either alpine or pioneer 1720. for rear speakers, get sony 6941 or pioneer 6902. for woofer, get pioneer 308 or cervin wega vmax woofer. jbl cs 60.4 amp for front n rear speakers and a good monolock for the woofers.
if you dont want woofer, just remove the woofer from the above setup and addd two more speakers on the rear. front channel will then be used for front fill in as 2 components can not overcome 4 speakers. my suggestion is DONT buy kenwood 718. bass might be good but everything else is crap