Be a pro acceleration, impossible to increase.

Acceleration is impossible to increase once you have maxed it out in the skill tree. There are no salary perks that increase acceleration at all. This means that for my build I can't get acceleration above 88 which is not that high and it permanently locks the X-factors for Elite Edges and Wheels. Add more levels to the skill tree or give acceleration exp for clean zone entries or something. Why make certain atributes unupgradadable?