While the rules regarding personal upgrades seem straightforward enough, I'm still left wondering whether or not a player may use multiple personal upgrades to increase the same ability.
You can gain a total of three personal upgrades, regardless of the source. Each personal upgrade item has a model number: mk 1, mk 2, or mk 3. A mk 1 personal upgrade grants you +2 points to a single ability score, a mk 2 personal upgrade grants +4 points to a single ability score, and a mk 3 personal upgrade grants you +6 points to a single ability score. Each of your personal upgrades must be a different model number (for example, you cannot have three mk 1 upgrades, but you can have a mk 1, a mk 2, and a mk 3).
They all mention granting a bonus to a single ability score. The wording leads me to believe that they should be applied to different ability scores. Am I reading the ruling right?