This is our newly completed stock radio, worked over by Jeff Anderson from miata.net. he changed the output range of the headrest speakers from tweeter-only frequencies to full-range output. he also replaced all of the burned out lights since they fail every 40,000 miles or so. there is a problem with the miata radio that prohibits it from turning on in humid conditions because condensation gets into one of the plugs and shorts the circuit out, so he prevented that from happening by jumpering the plugs in question. then he modified the bass-adjustment knob to give 1/8 of a turn more range of adjustment, and finally added a male stereo plug (the green one on the right) so we can hook a portable CD player up and retain the non-theif-attractive stock radio.
jeff also offered suggestions about how to re-wire the stock HRSP wiring as Mazda miswired almost all of the miatas from the factory. it turns out, ours were wired out of phase and out of stereo!
**oh my god, this is the best stereo upgrade i have ever heard for what we paid! $255 for new headrest speakers, new door speakers and this worked over radio. everything installed so cleanly, i am amazed Mazda didn't offer this system from the factory. you can feel the bass in your back from the new headrest speakers, the door speakers sound incredible, and the new radio is much brighter than before. i noticed that now we have the headrest speaker level turned to about 1/4-1/2 whereas before, we needed to crank it to about 3/4 to get any meaningful sound out of them. bass, treble and midrange have all improved now. very very satisfied here! :-D