Things are looking promising!
I'm not very good at explaining things, so excuse my 'rambling'... 
The original setup gives you 3 prompts for a standard turn. For example, "Prepare to turn right in 1/2 a mile... Prepare to turn right in 1/4 mile...Take the next right". I decided to try to eliminate the prompt in the middle. From what I can tell, this is triggered by the line starting with "300". I just went ahead and deleted every line that started with "300". Sure enough, she no longer gives that prompt! Everything else still works fine. One problem with deleting ALL the lines starting with "300" though. If I approach a turn where I need to make a left, then an immediate right, she fails to give the "then turn right" prompt, and I also don't get the "Take the next right" after I've made the left. I think I'm going to have to remove only SOME of the "300" lines.
I will have to experiment with changing some of the other parameters. So far, I'm pretty sure of a few things:
- [*:166vjb7k]The beginning number is the current distance to the maneuver. The value is in thousandths of a mile (e.g. 1000 = 1 mile, 500 = 1/2 mile, etc... This determines when the prompt is triggered.
[*:166vjb7k]The "minsilence=x" is the minimum amount of time (in seconds) that must pass since the last prompt, before the current prompt can be triggered
[*:166vjb7k]"X" is the number of streets you'll pass before the maneuver (The nav determines the value of X). The maneuver is included in this count, so is X has a value greater than 1 (X>1) she will say "Take the 2nd (3rd, etc.) left/right". In the "vocal" column, the %X dictates what she says (e.g. X=2, say "Second", X=3, say "Third")
[*:166vjb7k]The value of "*" in "%*" tells her to say "right" or "left"
I did try to make her say "circle" instead of "roundabout" with no luck. I though that replacing "Enter the roundabout roundabout, roundabout" with "Enter the circle circle, circle" might get her to say "circle", but it didn't work. When I went to a local traffic circle to test it, she just said nothing. I didn't crash or lockup the system though, it continued with normal prompts on my way back home.
Tips for experimenting on your own:
- [*:166vjb7k]Use Windows Notepad to edit the .csv file, then just save it. Excel will add its own format to the file and make it useless
[*:166vjb7k]Remember to re-zip the "config" folder and the 4 other files (The 2 flag bitmaps, content.nng, and info.ini), and name it "Voice_TTS-nua-eng-us-f1.zip"
[*:166vjb7k]I didn't have any luck using the settings menu to load the new zip file. It continued to use the original for some reason. I ended up just transferring it with WinCE
[*:166vjb7k]There is no need to reload the language file after it has been copied back to the AVIC. A regular reboot will load it fine. I guess the system unzips the file during boot (no wonder why the boot time is long...
)
Steps to transfer the file to the AVIC (unless you can figure out an easier method):
- [*:166vjb7k]Make sure you have a backup of the original "Voice_TTS-nua-eng-us-f1.zip" in case you need to reinstall it!
[*:166vjb7k]Put the Testmode and MiTACAP folders, along with your edited .zip file on the SD card
[*:166vjb7k]Insert the SD card and turn on the car
[*:166vjb7k]After it has finished, click the Start menu and select "Programs, Windows Explorer"
[*:166vjb7k]Open your SD card folder (double-click, or select, then "File-->Open")
[*:166vjb7k]Select the zip file, then "Edit-->Copy"
[*:166vjb7k]Navigate to the "APL2\iGo\CONTENT\VOICE" folder on the flash disk
[*:166vjb7k]Select "File-->Paste", and choose "Yes" to overwrite the existing one
[*:166vjb7k]Remove the SD card and reboot
Hopefully, I haven't been too confusing. I think if we put our heads together, we can make this thing work the way WE want it to, instead of how Pioneer THINKS we want it to... 
IMPORTANT! - Use my instructions at your own risk! I am not responsible for any errors
Have fun!
-Eric