I called Mensa and was told that the highest score for MSAT possible is 99.9 percentile, which means 145 IQ sd15 and rarity of 1 in 1000 people.

Also the MSAT has 40 minutes time limit which is very short in my opinion. I completed all 36 questions but I'm only able to check some questions that i'm unsure and don't have enough time to fully check all questions for careless mistakes.