MIKEB4583

Tecnically u can use the stock set up, but you probably won't want to. Heres why; if you stay with your stock head unit, you will have to use amps that have a High level in-put on them, or get a high-to-low level adapter. What this does is take the amplified signal comming from your radio, (we tap in to the spkr wires to achieve this) and turns it into a low level signal that your amp can use to them re-amplify the signal. This greatly reduces your over-all sound quality. A decient after market deck will have RCA out puts. All amps have RCA in-puts.
A good deck will have 3 pairs of out-puts total: front, rear, and sub (somtiems called non-fading out put) When installed proplerly the seperate out puts will allow you to ajust the volume of the sub, with out changing your bass in your spkrs. With the stock set up, if you want more bump, turn up your bass, but then your spkrs will start distorting Turn bass down, spkrs aren't distorting, but now the sub is not bumping.

Get an after-martket deck with 3 pre-outs, and you won't be dissapointed.

Mike @ Magnolia Audio Video

MIKEB4583

Any single or double din unit will fit into your 04. A nice head unit w/ mp3 and 3 pre outs will run you about 250 and up. I have free install w/ purchase of a deck and the parts will cost 35. (dash kit, and wire harness; we leave the stock harnes in tack.) And we will put your dash back to stock at any time free of charge.

Mike @ ROSEVILLE Magnolia

herbXT

This really depends on how your final system is going to be. If you want an eleborate system such as new speakers, subs, a few amps and a lot tweaking capabilities. Then it is worth spending money on a new head unit and changer. (Remember you already have a tape deck and CD changer which means that if you want to buy an after market head unit you need at least a deck and a changer or an in-dash changer)

However, if you are just adding a pair of subs using amps driving them. You can buy amps with speaker level inputs and then you don't need to buy new head units and changers. Greatly simplifying the system and your hard earned cash.

I agree an aftermarket unit has alot of neat features that is great for building up a nice system. (Plus they look good and flashy to show off to friends..... and thieves) But if you just want a couple of subs then I don't see any reason to buy an aftermarket head unit for what you are asking.

herbXT

You are getting to the heart of the matter. What is the purpose of the upgrade and what does the upgrade do?

If you want to fix the midrange-high then you should put you money into upgrading speakers driven by a nice amp. (i.e. separates with a real, properly designed x-over). Some quality amps have very good and adjustable x-overs on board that compliments stock head unit quite well.

It is true that if you want somthing very exotic / sound-off quality system then a head unit upgrade with the latest technology (e.g. I am excited to start seeing new head unit with digital time delays as in home theater) will be a great foundation. But in practice what you are after should be amps and speaker upgrades first. After all, if you still not happy then buy the head unit. But an indash aftermarket unit will be pricey.