Okay, just wanted to clarify a little misconception all of you have seem to be told by your local stereo shop...

Your factory deck has 18 watts of power times two for the two speaker outputs...
The "MOSFET" amplifier chip in your deck draws a max of 6 amps of current...

18 divided by 6 is 3 volts AC.

That being said, if you replace your factory radio with an inexpensive radio (ie kenwood 2028, etc.) or a Sony, Jensen, etc. these decks only have a 2 volt max output through the RCA's... and realistically, they don't output more than 1.85 volts...This means that you will not be able to get the full output out of the factory amp as you are not giving it enough voltage... If you invest in a Nakamichi CD400 CD500, Blaupunkt Bremen MP74, Kenwood KDC-X589 KDC-X789 KDC-X889, Clarion DRZ855MP DRZ955MC DRZ9255, Eclipse CD5425 CD5435, etc. (A high quality deck with true RCA output over 3.5 volts) your factory amp will reach its true potential.

That being said, you're wondering why I didn't mention alpine, etc... Well, output impedance also matters... If a deck has a 600 OHM output impedance as opposed to 55 OHMS, and the voltage is the same, the 55 OHM deck will provide more current...

And subwoofer volume control after you replace your deck... Well, it is possible if your stereo shop has an installer that is knowledgeable enough to trace back the factory deck wires going to the amp that is in the passenger side footwell under the carpet and under the metal plate that is bolted to the floor, splits up the wires going to the factory amp (there are wires there for four channels) and hooks up the decks Front RCA's to the front speaker inputs of the amplifier, and the Subwoofer RCA's from the deck to the Subwoofer inputs of the amp...

How do I know all of this? Well, I have been an installer for about nine years (now I mostly do sales, management,and the occasional "high-end" custom install), and I own a Crossfire that I have installed about twenty different decks in to... Which one lives in my dash? It's a Blaupunkt San Francisco from 2001 that I had new in box sitting in my closet for years... That is until the new Blaupunkt Bremen replacement is available...

At the shop I work at, I guinea pig all of the new product (mostly the more expensive product) in my own car prior to us purchasing it... If you have any questions, drop me a mail or PM and I will help you as much as I can...

Also attached, you will find a copy of the audio diagram in our cars that you can bring to your local install shop... All they have to do is separate the wires at the/going to the amp from the radio, run two extra speaker wires to behind the radio, and solder on RCA ends...then plug them into the radio of your choice...

Enjoy!