Brunswick Bowling Balls. The Ambitious II uses a proven hour glass shaped core to create a highly angular ball reaction. High RG core systems have been very popular with International bowlers because of their ability to delay hooking to the back part of the lane. PowerKoil Response coverstock is a new way to describe the Response or how fasthard the ball will respond to friction. Together, the High RG core system and PowerKoil Response coverstock create an aggressive reactive coverstock ball that saves most of it's hooking for the back ends. The Ambitious II will match up on medium oily to medium dry lane conditions.