I would assume a good place would be below the power mirror control knob on the driver side and the same place on the passenger. I have never actually done it but it appears to be the best spot for it (just the right height and position). the only other place I can think of is on the door as close to the dash as possible and have directional tweeters.
I'm about to mount some tweeters in my car. I don't think the interior mirror control caps are flat enough to mount a tweeter. I think I'm going to mount mine into the un-used portion of the stock speaker grilles, seems like it's the easiest place to mount.
no if you push down on it a little you can feed the edge of the wire in between the top of the tube and the dash. you can reach up from the bottom and find the wires pretty easily too. however if you cant, a small hole in the tubing is OK. if you ever remove them a small piece of tape will close it right up.
4k Hz & up become more & more directional going up to 20k where most humans max out at. Kick panels are supposely soundstage sweetspot, but any where ear level pointed toward you is best in my experiences. Steeda's set up probable bounces off glass a little though.
Mounting the tweeters in the vent is certainly the easiest place to mount because you don't have to drill a 1" hole, but what happens when you turn on the A/C and send air to the windows? You've blocked off both vents, so I'd assume more air goes to the windhsield vent.
I'm going back to Boston soon, so I'll be needing the heating system to function on the windows, seems like the corner vents don't really do anything, only the large one below the windshield has any affect.
That's not a bad idea at all! I checked out the mounting for my tweeters in the HVAC vent, not even close, so I gotta find somewhere else. I was thinking of drilling a hole in the un-used portion of the stock speaker grille. I'd rather not have the highs right at my ears screaming, I get a headache already from my speakers that produce mostly highs.