When you have to take out the four rival gangs for the underboss mission all you have to do is go to each doctor in each part of town and take them out silently then head over to your gangs mansion and save it quit and then come back on to the game dont leave the mansion for a while and do quothealth cheatquot quot5000quot cheat after this do quothealth cheatquot one more time it should make a louder noise like metal go out side you will still see the four blue blips but drive to them and all you have to do is plant a bomb easy its wicked