"Load" in this case is largely calculated based in the MAF and reflects the volumetric efficiency -- i.e. how much air (and therefore also fuel) is going through your engine compared with how much is theoretically possible. If the engine were naturally aspirated, the Load value would top out at 100%. Without source code for your ECU's firmware, it's somewhat difficult to say where the calculation (inside the ECU) would top out.
-Uwe-