hey, i have a 1999 grand prix and i am in the process of building a system for it..
i have a pioneer DEH-P7800MP head unit, infinity 50121 5 1.4'' 2-way speakers in both front doors, JBL 6 x 9'' 2-way loud speakers in the back, and the pioneer iPod adapter that lets me use my iPod threw my cd player. im not sure what to do with all of the settings and the 16 bar eq.. i have read the entier manual and tried to set it up as well as i could but i am still not sure what else i could do. once i get my next paycheck i want to get a 10'' sub but i am not sure what kind to get.. i want to to be really responsive and and have a lot of punch but i am not sure what kind to get. also i am going to get new tweeters and i wanted to get a door deadening kit but i have no idea if it will even improve the sound quality.

if anyone can help me out it would be very appreciated.
-James

 

the JL 10w6v2 sub powered by a JL 250/1 amp does a pretty good job

 

Before you buy ANY more gear, deaden the car as much as possible, that'll lower the noise floor, and give you better dynamics, focus, punch, etc.
Everything an SQ vehicle needs. That'll be money well spent before you get a sub. And when you do get a sub, make sure it's in a GOOD enclosure, otherwise it'll sound like *****.