I finally replaced the crappy Speedhut boost gauge with a new one. It calibrates to actual barometric pressure every time the engine starts. The instructions say it has to be wired to a 12V source that doesn't cut out during cranking in order to calibrate properly. Sure enough if you just wire it to a normal 12V that does cut out it gives weird readings. The tech rep told me that this would be the case. What circuit will do the trick in my 86 GN?