GM 3 BAR map reference??
 

so i bought a Gm 3 bar from banzai racing. nice unit with the plug and play harness. my question is i am running 25 psi my elevation is at 1800ft above seal level and i am not quite sure what to set settings to. i have read and read but no real clear answers.
Do i have to rescale the PIM map reference from 01-20 and the scale off set in the PIM or just leave the stock settings for Map reference and just Do like 6300/0 for PIM scale off set???
any help helps. and as for using my air compressor and volt testing i really dont think a air compressor puts out a consistent 25 psi with a guage on the tank that starts at 50psi to 400psi. so i am just lost lol

Well there are two schools of thought: scale the map reference so that local atmospheric pressure is zero and proceed from there (checking AFR's if altitude changes) or use some calibration that is meant for lower elevations and tune around it.

This issue comes up because there is no barometric pressure sensor like the FC and FD stock computer have. Nor are there any kind of fuel trims or self learning like a modern OBD II factory computer.