How should I upgrade my sound system?

Yeah for sure. Loose those 8's and 12. Grab two good 15" subs from Treo, RE, AA,DD,FI,AudioQue,JL...and put a real amp on those things. Ask around in car audio forums for a recomendation.It is going to be pricey compared to what you have but thats because you got some cheap sh!t. Look around, save up, and do it right the first time.