[JMcLellan]

To your specific question/request I do not have experience with this exact issue, or have experience with resolving but I wanted to chime in.

You need to get some diagnostics done to pinpoint what the issue is. I tend to agree with the working theory that the change in gear ratio is causing this but these cars are really complicated and it potentially could be other things. There has got to be someone who can go drive it and/or hook up something to your OBD port to do some readings.

Bummer to hear about this. I've heard great things about the wavetrac and how it transforms the driving experience of the car. Hopefully you get this resolved soon.