OK, i had a little progress today, but not really as much as i had hoped. Here's what i did:
-I mentioned in my original post that i had changed "roundabout" to "traffic circle" and "turn back" to "turn around". I've now changed "turn around" to "make a U turn". These have all been tested and work.
-I also mentioned that i slowed the voice speed down (from 50 to 40). This makes the voice slightly less irritating.
-I found a setting for each prompt type, that specifies a time period that must have past since the last prompt for that prompt to play. I changed some of these so that in many cases there will only be 2 prompts to turn instead of 4. If you are in the city stopping at alot of lights, or stuck in traffic, you will get more prompts then since the time period is more likely to pass. I think this is the best way to handle reducing the prompts. I tested this on my way home from work, and typically only received prompts at 1/2 mile, and make the next left/right, whereas on the way to work i would get 1/2 mile, 1/4 mile, 400 feet, and next left/right. The time period is also per maneuver so if you have two turns within a few seconds, you will still get the prompts for both.
-I found a 22khz version of Samantha from MioMap (ours is 11khz) and successfully got it working on the F after much trial and error, but it really doesn't sound that much better. It is slightly noticeable, but not the results I had hoped for. My VR also stopped working.
All of the changes I have made so far are in the commands.csv file within the TTS zip file. I will post this zip file in a few minutes for anyone that wants to try it
For the 22khz voice, you need to dump a bunch of files in the iGo\ScanSoft directory. I don't really want to post this yet until i figure out why the VR broke.
Also, there is a rules.ini file in the TTS zip file that defines how highway/exit numbers should be pronounced, but its not being used for some reason. Based on this file, 422 should be "four twenty two" and 202 should be "two oh two" but both are said with "hundred". I need to figure out why this file is not being used because it really annoys me being told to enter highway four hundred twenty two.