Hrmmm. If you're into SQ I'd suggest researching. Audio is quite the science...it's not as simple as just installing speakers and amps.

Currently I've been on DIYMA. I've been reading for over a year and I have a parts list currently but no install. That's my next step. I wouldn't say it's expensive but majority of your SQ comes from install...not parts.

Either way...I have an '04 Comp G. Here's my list so far...

Alpine CDA-9887
I wanted a nice double din touch screen but I would have to couple with a processor to make up for lack of clean signal. The 9887 also gives me very good options for active tuning from the drivers seat.

Audiocontrol DQS - supplement the processing from 9887 with amazing EQ options to help create a nice flat response

Sundown Audio SAX-100.4 amp
Great guys, looks to be a great amp too. Known for SPL; this is their first SQ amp.

a/d/s/ 346is front speakers
Going passive at first and possibly active later. First option is 320x2 from the SAX. If I go active it'll be 4x100

Rear "fill"
Mid-range (not mid-sub) speaker ranging from ~250hz thru 3000hz using differential bias from mono L/R inputs to the amp.
Hey Werewolf, confusion about L-R... - DIY Mobile Audio

I'm powering the "fill" with TXA-3002 (150x2)

My subwoofer is a DIYMA R12
DIYMA 12" Sub CLEARANCE ... until supplies last - DIY Mobile Audio
Unfortunately you can't purchase it anymore. It's powered by...

TXA-750D by Cadence.

The Cadence amps are great entry level amps. Kind of cheesy looking and cheap to feel but great bang for buck; especially for power output. They are not over-rated on power by any means. If I had the choice over I would use the IA series...specifically the iA2.

Cadence iA2 - Powermax Electronics

Anyways...this is my particular build centered around sound quality. I have yet to install but there's a lot of research to consider if you really wanna get it right. I'm usually on the DIYMA forums. I was looking through here to look for amp rack ideas, etc.