I traded in my Maz6 for the RX-8, with both sharing the "no aftermarket head unit in the dash" syndrome. With the 6, I bypassed the stock HU by running an Alpine in the glove box, controlled by the steering wheel controls. Worked great, except you never get to SEE what's playing.

Anyhow, I just had Sound Advice move the equipment (Boston Z6 front, Boston 10 inch 110 in the trunk, JL 500.1 and JL 300.4 bridged) into the RX-8. Decided to use the stock HU (Alpine given to my son for use in his Maz3, which already has a dash kit!). The amps and crossovers fit nicely in the spare tire well in the trunk (pics to follow). BTW, the Boston sub, which comes in a Boston box with passive radiator in the back, fit through the trunk opening with about an eighth of an inch to spare, and the JL amps, side by side, had about the same clearance in the spare tire well. Sometimes it helps to be lucky. http://www.bostonacoustics.com/ca_product.asp?ProductID=128

Not bad at all, considering the use of the stock radio and the use of the high level imputs (the JL amp has the built in ability to vary voltage sensitivity, so LOC aren't necessary http://www.jlaudio.com/amps/3004.html). Although it would be easy enough to put a HU in the glove box, it's nice to SEE the music displayed on the dash, as well as hear it.

Ya, ya, the stock head unit is not that bad... it certainly has decent enough sound quality.

I want to say for the record that it has come to the point where "speaker level" outputs from a factory radio are high quality especially when those "speaker level" signal don't actually drive speakers (which is the case with Bose system).

The IC's have gotten to the point where the high-voltage/high-current ones used for speaker level signals are very low distortion and have very high signal to noise ratios.

Anyway, my advice is don't upgrade your factory HU for sound quality reasons thinking that you have to have pre-amp outputs for quality sound. Only upgrade if it doesn't offer the features you want.

-Mr. Wigggles

Since the aftermarket radio would be in the glove box, many of the "features" wouldn't be readily accessible either. What I am missing is an MP3 player with the stock (non-Bose) headunit. I wouldn't spend the money for the Mazda MP3 player add on.

We tapped into the rear speakers outputs (speakers now disconnected) for the sub, so the fader control acts as a subwoofer volume control.

Cool. So how's it sound?? :D

Not bad. It did sound better with the Alpine unit in the Mazda6, but I think with a little tuning it will be more than acceptable. One of the problems is that there is a large increase in volume with each numeric increase in the volume control. I will turn the gains all the way down, which should help.

I'm also using a smaller, different sub (10" Boston in small box vs. 12" Image Dynamics Max in big box, total weight 70 pounds!) so the bottom end isn't as deep. Separation and imaging aren't bad. I'd say the sound would be about 20% better overall with the Alpine versus stock. With lesser speakers than the Boston Z6's, the difference might not even be noticeable. Better than the stock head unit on the Mazda6.

After listening to the Boston Z's through the stock HU, I'm more than satisfied. It may not have the ultimate sheen and detailing an aftermarket HU might bring, but I'd say it's at least 90% as good when listening at rest. With the engine humming and the exhaust singing, you won't know the difference.

Hey, if I don't put an aftermarket HU in the 8, then I can put it in my wife's Mazda3!! Good deal, and brownie points earned with the boss.