Trying to improve Concert Sound III,,Intgrd AMP
 

Im trying to improve the sound of my 2000 Century. Its nice this thing has 8 speakers. That extra 4" 4ohm speaker does really help with the mid. I got some Cerwin Vega VS series 4" 4ohm 2-ways to put in its place,,, and it was horrible. There was no low, no mid and no highs. Its got to be those speakers, so I reinstalled the factory 4".
I put pioneer 6" in the doors and it has great sound. These speakers were free and the ohms were higher,, 4ohms,, factory door is 2ohms. It has better high, not as good mid and bout same low.
I work at a body shop and swap out the 6x9s 10ohms for some out of a 2002 Grand Marcis. They sound great, but not what Im used to.

I need more power and a sub, but want to keep factory steering whel controls..

So my question is, what to do about this??

A sound processor... I see Kenwood has one for $400. "they say" you can keep factory HU.

How to bypass or improve intergrated AMP??

Thanks

I didn't say the correct about the 6x9s...the factory ones from the century are 2ohms...the Marquis ones are a wopping 10ohms..
So I've leaned alot about my factory monsoon amp...they say it has around 200w rms...it sounds more like 125w rms... maybe with quality speakers it will do better.tho this century has one of the best factory sounds.
I got a wiring diagram from Crutchfield for hu and amp....it would be fairly easy to install after market amps.. tho I've read this 8 speaker system with monsoon amp does alright with better speakers..
I'm looking at soundstream trualantula speakers and t6 sub..
If u put an inline rca adapter...cut into the rear 4" if u have...if not the the door speakers... befire the amp..