Hi everyone! I searched the forum for the answer to this question but thousands of threads came up. I even tried narrowing the search. Sorry in advance for what will most likely be a question that has been asked many times before.
What are the front and rear speaker sizes on the Bose system for a 2003? Also, is there an individual amp for each speaker? Or one for the whole system? Lastly, what customizing should I expect to do to make aftermarket speakers fit? Thanks a lot!

 

5-1/4!

 

Check the audio section, I'm sure you'll find some answers. I believe your front are 6.25. If you have a coupe, the rears may be 6.25 as well. Vert's and FRC are smaller. The fronts are amp'd.
Give Dennis at Double D Mods a shout. Great guy, great service and very knowledgable. Good luck.

 

The audio section has good info. The front is a dual speaker module. There is a larger "woofer" which is amplified in the module and a smaller "tweeter" which is powered from the head unit. The rears are just a smaller round cone.

The head unit feeds some sort of line level signals to another processing module behind the dash. I believe this module feeds the amps in the front doors. It also feeds line level type signals back to the head unit internal amp to power the "tweeters" and rear speakers. So, the doors don't receive full range audio from the amp in the head unit and the "woofer" is built into the speaker module in such a way that it can't easily be replaced. Overall, this means you really can't just replace the speakers and leave the rest of the system in place.

I suspect you could jumper the line out and line in signals on the head unit and get rid of that extra processing unit. Then, you'd get full range audio from the head unit to the doors and rear speakers. You could also likely use a S-10 head unit because they are the same except they don't have the extra line in and out for the audio processor. They might not support the CD changer if you want or have that.

Your other option is to just replace the head unit too.

 

How Can I get better sound while keeping the bose head unit?
Upgrade speakers
The easiest way to get better sound from the stock head unit is to simply swap out the in door 'twiddlers' with after market 3.5” speakers. You also have the option of swapping out the rear speakers with 5.25” speakers for the frc/z06 and convertables, and a 6.5" speaker for the coupes.

Adding an amplifier
To add a subwoofer or to give your aftermarket speakers more power you will need an aftermarket amplifier. Please note you will not be able to power the stock bose speakers with an aftermarket amplifier. If you are keeping the stock head unit you will need a bose interface (please note: When tapping into the stock wiring, the low frequencies for bass ARE NOT present at the twiddlers. The 8" sub in the doors or behind the h/u must be tapped when adding a sub). A popular model for the c5's are the 'soundgate' adapters or pac-audio interfaces. This will allow you to retain the stock headunit and all of the stock features associated with the head unit such as retained accessory power and automatic volume compensation even the stock speakers if you only wish to only add a subwoofer. The bose interface will give you pre-amp level outputs that you can run to the rca jacks of your amplifier.

 

Thanks for the info everyone. A couple of days ago I swapped for an aftermarket head unit also using the PAC-ROM Vette1. I thought I would be content with the stock speakers. I was wrong. I want to change the speakers all around. I already have a good digital JL Audio amp from a previous car. I will not be adding a sub-woofer. I just want all of the Bose components out of there and good speakers in their place.

 

Well, that would have been good info to put in your first post.....

You'll have to make a plate to mount different door speakers so the exact size really doesn't matter. Make a plate to put a good set ot 6.5" components in the doors and just forget about the rears, you don't need them.