I highly recommend JL Audio. They are a little pricey, but with some research you can find a good deal on them. I am a firm believer in the old saying, "You get what you pay for."
It really depends on your budget sound preferrence, and what you are powering them with. If you are running ANY type of quality component set, they are gonna need an external amp for optimal sound quality.

 

Infinity all the way! IMO, Infinity components, JBL subs and amps. Both are owned by Harman Audio Great stuff

 

I found a pretty good site that some people probably already know about but they are running some great deals right now, its called techronics.. here is the link.

http://www.techronics.com/index.cfm?...TOKEN=43775752

 

What size component speakers will I need for my 2003 2500hd CCSB Silverado? I'm looking to replace the front and rears, get two 12" subs, and possibly get a new headunit. I would like to keep the stock headunit because I just think it looks better than a flashy aftermarket one, but I know it would sound better with an aftermarket one. Does anyone know of any quality headunits that don't look like they belong in a Daewoo?

 

6 3/4 " speakers in front and rear, cruthfield.com is a great place to go and see what size speakers will fit in your truck. They also sell tons of car audio stuff.

 

i have some jbl components up front and infinity 4x6s in back hooked up to a jbl amp. And they sound damn good in my opinion. now i just need a sub to handle my amp.

 

I ran some 6.5 inch 3 way components from JL Audio, they are the XR's had a JL Audio 300/2 amp running them and they sounded Great!! My four 12" JL w6v2 subs couldent drown them out. I also recomend the JL Audio ZR component line they are newer than the XR's i ran. You cant go wrong with JL Audio!!!