If you look in the value files there's a GT500 transfer curve for JLT intake. It doesn't say if it's the plastic one (123mm) or the carbon fiber (127mm). You could take it and scale the numbers back by 33% for your 83 mm tube. This should give you a rough starting guide.
There's a formula for converting counts to volts and volts to counts. I don't know it by heart but have it at home. If you have Don Lasota's manual it's in there. If I remember tonight I'll get it posted up but you really don't need to know the volts. What do you need volts for? just reference?