I need sound system help?

well i got my car hooked up to a 12inch sub with a jbl amp for the sub and all the speakers in the frnt nd rear were changed to 6inch. it sounds good well alright it seems that i have alot more b then sound. so now im guessing i need an amp for the speakers, but im pretty clueless on wat i need to improve since i did not do the sound system work and i am a noob at systems. any help in what brand amp i need and how many watts would be good enough can help.