I just did the upgrade and the headphone jack readings are a little high. It goes up to around 17-20V and drops back to 0V. I've read before that the speedball values might be higher than the stock crack (my stock crack measured around 7-8V before dropping) but measuring double the voltage seemed like i should check with someone first.
All of my other voltage checks are fine (largest deviation is 4%)
All of my other voltage checks are fine (largest deviation is 4%)