Okay, i'm from north cali, where car audio is taken extremely seriously. and i have been into the car audio scene since i was like 12...so i have some experiance with multiple brands, styeles and sounds.
I'll keep this simple, and list what i personally have found to be good product.
as far as sub-woofers go...i would go Cerwin Vega, Planet Audio, Image Dynamics, Eclipse, Hi-fonics, Kove Audio, Soundstream, PPI, DEI, Nakamichi..(beautiful sound quality)INfinity Kappa/Kappa Perfect, Audiobahn high end subs are good peices as well. Memphis audio, Polk, Hollywood, Boston Acoustics...subs on a budget...Lanzar, Pyle, JBL, pioneer, Fusion...infinity refernce
brands to stay away from...mobile authority, rockford fosgate, "thump", Sony, Kenwood, JVC, advent, volfenhag...ive had nothing but bad experiances with these brands...this is a short list cuz these are the most common "garbage" brands.
CD decks i like....Clarion, Alpine Eclipse, higher end Pioneer (premier) McIntosh(you WILL pay for it)Nakamichi (it looks bland, but its good stuff, it has a real clean classy look) and Most panasonic
brands to stay away from: blaupunkt, Sony, low end pioneer, Kenwood, low end panasonic, sanyo, Road gear(lol), eww eww eww and stay away from JVC at all costs...i tell you....3 out of 5 JVCs are returned everytime we sell them.(not my choice)
Amps....Ample, A/D/S, crossfire, Pheonix gold, Cerwin Vega, Zapco, Hi-fonics, JBL is okay, but i like to stick to brands that stick to what they are known for...their subs. Nakamichi, Planet Audio, Lanzar, some of the Power Acoustic Farenhiet series amps are good pieces.
im a little tired right now, i just got home, but if there are any questions, leave them, and i will respond, yuo can ask me just about anything, and i can probably help....i hope this was helpful to some of you.