Before I go out and get a header, subs and new speakers, I was wondering if the stock CD player is comparable to the $100+ such as Pioneer or Aiwa. If you have any reasons why to keep the stock or why to get rid of it, please post them!

 

A new HU will def. show you an improvement. I was thinking about keeping the stock HU, if u did, you would have to get RCA converters so that you could send those to the amps. I would suggest you go with a new HU. If you don't want to spend much, look into the lower end Alpine or Pioneer HU's.

 

I would be evenly divided on the question. It would depend on what you want, and what are your motovations in changing.
In general the stockhead unit is just fine as a source unit. CD players in general have extremely high specifications, to the point that differences are not audable to the human ear, or in a standard configuration. 20-20,000 hertz with at least 90 Db of channel seperation with a 90+ DB of Signal to noise is standard on all car CD players, and the Mazda Headunit is no exception. You can find numbers better than that, but you will not be able to hear a difference.
Any reputably built CD player in a car will smoke the older cassette units for great sound.
The FM section is not bad either. Sure you can find better FM seperation numbers, or better signal rejection numbers, but the truth in FM is you are only as good as the FM transmitter itself. Most of the time if a FM signal sounds crappy, it is fringe reception, or a lousy source (radio transmitter).
The controls of the stock are easy to use, and include a low, mid and high frequency adjustment, something allot of basic aftermarket units don't do. It also has an audable search in song feature that many aftermarket CD units do not have.
Where it falls short is amplification, no question about it. With ratings of 12-15 watts, and distortion starting at 8 watts, the stock unit won't drive a concert hall.
It is been pointed out in several other post- but not enough amp can be more dangerous than too much amp for speakers. Too little amp and you get distortion and worse, signal clipping, a great way to invite replacement speakers into your life!
This caveat holds true to most aftermaket headunits too. They may claim 35 or 45 watts of amp, but at what distortion levels? Simple fact is if a headunit amp section is as good as a aftermarker outboard amp, it would probably be the same size as the outboard- large.
The connection between the stock headunit and an aftermarket can is easy enough, either us Line Out Converters (LOCs) to "convert" the "amplified" signal out of the headunit into a RCA friendly signal, or purchase am amp that allows a high current signal end. (Xtant does this, and most people will not sneeze at Xtant as being a flea market brand).
So one can take the stock headunit, and make it the heart of a decent upgrade- why then would anyone change the headunit? In a word, features.
If you are like many of us who have aftermarket audio, the features, the whistles and bells, are what tweaked us into getting a new headunit. I like the cabin sound equalization system and the digital FM signal of my Blaupunkt. I have a Premier P-9 in the sound car for the triamplification features and the amazing equalizer. Many people are in love with thier new displays that a aftermarket unit will provide.
If there are features you want out there, then the world is your oyster- make a list of the features you would like, and then search for a unit that has the features you want.
Hope this helps a little.

 

I believe even the $100+ Pioneer and Aiwa are much better than the stock CD player. Just stick with the big brands (don't get anything from Boss, Plye, Road gear..) and you should be pretty safe.

The advantages to getting an aftermarket deck gives you better sound, the ease of upgrading your sound system (provided you get those with RCA outs) and not to mention the "bells and whistles".

 

Thanks for all the help, I will do a little more research with your input. I appreciate the time you took (David esp.) to answer my questions!