Did some more tinkering with the gauges. The OBD module had a built-in terminator that defaulted to 'on' and was messing up the bus (the modules are daisy-chained). Turning that off totally solved the issue with that gauge. The secondary display module is still flaky but I'll need to do some more troubleshooting...might need to be sent in for warranty repair.
I also discovered that my boost gauge was only going to 18psi. I'm guessing that the vacuum line on the BOV is limited to wastegate pressure...I moved the tap over to the 3port line and it looks good. It's apparent that Shane taps in at that spot.
It's such a novelty to have a car that runs right! I was on the back-roads near my Dad's house (WI)...doing pulls to test the gauges. I'd almost forgot why I bought the car.
