Those cars had more than 500bhp and the Group S cars that were suppose to replace the mad wild days of Group B were rumoured to have well over 1000bhp....but Group B and Group S were killed off due to safety....
Actually no, the group S cars were actually limited to 300hp, a concept that was later resused in the later stages of the group A era. The point of group S was to dispense with the homologation rules.