With the mid needle, all I know is that stock is 99% of time fluch with the carb body.
It would be interesting to read up about the mid-speed needle, all I know from past reading is that you shouldnt really mess around with it unless you are a tuning pro! I have, and it did seem to have an effect, especially the bottom end, but I never really went more than a few hours.
Car-less (Velox V10 or 733) // RB T10.5"+" (JB Modified) // Bluebird BMS-990DMG (St) & BMS-631 (T/B) // ATS 16% // Capricorn Wheels // Protoform
"70% of the time, it works ALL the time"