http://www.mazdas247.com/forum/showthread.php?t=123685785&highlight=windshield+noise
Here is a couple of quotes:
"Sounds like you're talking about a common complaint with MS3s. I think people call it "cowl creak" or "crowning creak" or something like that..."
"I had this problem and was able to fix it. Most of you guys who bought your speed 3's in warmer weather are not aware of all the rattles that come out when it gets cooler. I bought my car last november and spent a lot of time trying to figure this out. It is the cowl that is rattling against the windshield and there is a very easy way to fix it. Get two plastic spackle knives and some very thick electrical tape. I can't remember what type I used but it was not very sticky and was much thicker than normal electrical tape, it also had a white backing on it. I got it at home depot. Take the screws out of either side of the cowl. You can remove the wipers as well to take off the entire cowl, but I found this was not necessary and it was two difficult to get the wiper arms off. Anyway cut a piece of the tape that is the same length as the entire cowl. Start by prying one end of the cowl up with one knife and pushing the tape under with the other, I found it was easier with the sticky side up. Do this across the entire cowl, it will get more difficult towards the middle because the wiper arms hold the cowl down. Once done put the screws back in and your good to go. You do not need to have any of the tape exposed so you can't even tell you modified it and the sound is gone. By the way the sound only gets worse as the weather gets colder, so take of this asap. I hope this helps, sorry I don't have any pics, but I am in Africa and won't be home until January."
"Dread... you are THE MAN! As I was doing this project, I kept thinking, "there's no way this is going to get rid of the clickity clackity noise I hear from my dashboard. I followed Dread's instructions (I actually only did the driver side of the cowl as that is where my noise was coming from). After 10 minutes (it was actually a bit tricky until I figured out a nice technique which I will describe later), I got in the car for a test drive convinced that the noise would persist. I was completely shocked when the only thing I heard was the hum of my Speed3 again! I couldn't believe it."
"Anyway, here's some more details I can add to Dread's post... I used "127 Linerless Rubber Splice Tape." It's the only thing I could find that fit Dread's description... thick electrical tape. I'm not sure if that's what he used or not. It was pretty difficult getting the tape down in the space you have pried open. I started at the side closest to the driver's door as that was the easiest part to pry open. Lay out the cut piece of tape (sticky side up) on the windshield. If you put the plastic putty knife ON TOP of the tape (but not touching it) you can create the space to tuck the tape in. The nice thing is that this tape wasn't extremely sticky, so it was not too tacky to work with. With a little practice, you'll get the tape in there and you can screw the cowl tight again. I actually did use a blade to cut off the excess as the cowl is not straight, so certain parts had more tape sticking out than others. (I'm curious how you did this Dread... when you put all the tape in there, how did you keep it from bunching up on you?). Anyway, your call if you want to trim it or tuck it all down in there. The bottom line is that if you have a vibrating, clicking, rattle, popping sound coming from the vicinity of your dash or windshield... give Dread's fix a try. Saved me a 90 mile useless trip to my dealership. Thanks, Dread!"
"I have it when it is cold, its like a little squeak, I still have to bring it back to the dealer, but he said it is a common problem and they will be able to fix it by putting foam between the cowl and the windshield."
