Hey Everyone,
I am going to have to agree on looking into changing out the head unit first. I went the other route as I had the stock 6 disk in dash Serious Radio Head Unit and first tried to build up my system around it. I did all my speakers, subs, and amps first and did high low converters off the stock unit. It sounded good, but not great. Then I changed out my Head Unit and as far as clarity an sound improvement, it made all the difference in the world! Here is what I am running in mine.
A Clarion DXZ785USB Head Unit
A Clarion Custom Modified 24 band Digital EQ with DSP Processing
Rockford Fosgate X162S 6-1/2" 2-way Component Speakers, and tweeters with Crossovers in the front doors, and dash.
Rockford Fosgate T1682S 6"x8" 2-way Component speakers, and tweeters with crossovers in the rear pillars
Two Performance Technique 10" Chromed Comp Subs mounted inverted in a tuned and sealed custom box
Two Rockford Fosgate T1500-1bd 1500W Mono Amplifiers which are now driving the Subs
and a Boss 20 Farad Capacitor With Digital Voltage Display And Illumination to keep the lights from flickeing, and added Dyno Mat insulation throughout!
Chromed Autotek SX-2300 350 W x 2 Amplifier with the Gold Plated Chrysler Logo built into the casing
Chromed Performance Technique ICBM-774 1000 WATT 4-CH AMP
So I would have to say, I would go for changing out the head unit first. To mr that would probably give you the biggest bang for the buck.
Best of luck, and please let us know what you decide to do, and maybe post a pic or two. Us Cruiser Guys luv pic's!
Go easy,
Candyman