MAP or MGP for fuel table

I notice you used MAP as the load signal in the fuel table. My Link G4 X pro ECU is tuned using MGP in the fuel table instead. I am somewhat confused about this and thought MAP should be used, however I found this discussion on the link forum supporting the use of MGP: http://forums.linkecu.com/index.php?/topic/2609-map-or-mgp-for-fuel-table/

Can you help me understand the rationale for choosing one method over the other?

The thread that you linked to explains the difference between the two load options well. MGP is the difference between baro and MAP and hence accounts for changes in barometric air pressure. MGP is the preferred/recommended option, particularly if you're expecting to see large fluctuations in altitude and hence baro air pressure. The point is that the engine's VE doesn't change with altitude, it's the air density that changes, so we're getting the same volume of air into the cylinder but that volume contains less oxygen.

Things are a little more complex in a turbocharged engine as we can maintain the same boost potentially as altitude increases but this results in the exhaust manifold pressure increasing - We're working the turbo harder to maintain boost as baro pressure drops. This means you're still likely to see some fuelling discrepancies creeping in with a turbocharged engine when spanning large changes in altitude unless you can also account for EMAP in a compensation.