MAP Configuration

I'm tunning in a city of high altitude, which means my atmospheric pressure is about 77 kPa (Bogotá, Colombia). As I set the MAP sensor that I have (GM MAP 1 Bar sensor), with the corresponding configuration integrated in the ECU (Haltech Platinum Sport 1000), I have a reading around of -20 kPa, how would this afect the table configuration? Should I start tunning from this point?

Thank you

hello if it is relevant to the atmospheric pressure in your area then it is ok