I recently purchased and installed the $142 auto dimming mirror from MazdaStuff.com. Three things I noted during installation: The plastic piece meant to cover the wire from the mirror mount on the windshield, to the head lliner, is too short. I added a small piece of foam tape and plastic to fill in the difference. The + wire to the electrical connector attaches to a blue wire/pink stripe. The green wire with black stripe has no power when the key is in the ON position. Finally, there are no clips along the pillar from the header to the dash. I used some other fasteners while being careful not to interfere with the air bag mechanism.

I also found the K&N Cold Air kit for $220. I installed that without instance. The pictures in their instructions are a bit hard to see.
Prying the plastic PCV piece out of the original intake hose is a bit tough. The bushing that gets installed from under the car, should go to the passenger side of the pre-drilled hole. Do yourself a favor... replace that horn with something louderwhile your under there.

I will be installing the cassette player shortly.

I WILL BE LIMITING MY POSTS TO THE MAZDA 5 FORUM AFTER THIS. LOOK FOR ME THERE.