OK, looking at it more I see your point. The ZR1 offset and linear are -11.25 and 312.5. But your linear maxes at 256. I guess you'll have to use -11.25 and 256 and know that your MAP is going to be less and less accurate the further up you go. Like you said, everything else is scaled so the fact that the MAP is off as well is just something else to fudge. Trying to whip up a spreadsheet that would show actual to fudged MAP values.