Need an idea for a good sound quality system

Yea i have an 1990 gmc truck 1500. and i just have the stock speakers at the moment but i have a good stero just need some ideas of a system i can put in and how i am going to do it. My truck is just the cab with the bench seat in it. I want to add some speakers and a 12 mabey but i have no idea how im goin to mount it. im looking for sound quality not just a lot of bumping just so you can hear it a mile away i dont care about that just good sound qualtity. If you guys have been in a hummer and heard there factory stero system its not too loud just right, mabey have it just a litle louder. I just need some ideas on wat to buy and how im going to mount it inside my truck

Thank any post helps  

well what i would do is upgrade to a good cdplayer i recommend a alpine or jvc replace your stock 4x6s with kicker 4x6s buy a 10 inch alpine type s or kicker cvr 10. two kicker cvr's in a long truck box would be pretty loud id go with a 350.1 kicker amp or a 1200 watt amp bout any name brand that puts out at least 300 rms will work. the box will just sit behind the seat eather u can mount the amp on the back of the cab using silicone and selftaping screws or under the seat or on the box. and questions just ask  

Thanks you for the advice  

I would put in some 4x6 kickers like dark chevy said or some pioneers. then mount the amp under the seat on the floor. As far as the subs....depending on your seat style go look on youtube... ive seen some basic to some inovative box locations.  

for the simple way, replace the 4x6s, add maybe 1-2 10s, but 12s might move the seat too far forward. In my 93 I did some new lower door panels to do some 6 1/2s instead of the 4x6s as theres going to be a huge gap in sizes and sounds between a 4x6 and a 10 or 12, aka, lack of midbass