Well, I for one don't hate stealth missions, I don't really enjoy them either. After I walk onto that gold blip(as I do every mission) the cutscene starts.
Yada yada ride over to the insane asylum on the Red BMX(had to put it) XD. I sneak in on that tree so conveniently placed with a long branch on it just over the gate leading to the private property. I jump down and dash over to the door, that asylum orderly wont catch you if you sprint to it, but stay close to the wall just in case. When you get inside this isn't the real stealth test, he'll leave his post in a matter of seconds. Get to the door, walk to the near exit but don't go past the wall, stay on the left side. "I don't know, don't care, but he sure does yell a lot huh?" They'll disperse after that quote. When you get into the lounge, god help you WALK, don't run. open the door, watch for the guard who's looking both ways, open the door, but before you open the door, look at your map, there's a guard on his rounds out there, its happened to me about every three times I try it, he'll catch you as soon as you open the door. Go to Johnny, but do so in the middle of the hallway, there's a guard at the end of the hallway, talk to him, go to the showers, there's a guard in there,but wait till he starts walking then go into the laundry room, get the uniform, get to the guard, say you want your break, open the two doors, set off the switch, free Johnny, then meet up with him, then go back to the lounge, the doors will get blocked off, but one door once again, conveniently doesn't go all the way, then lift it, then find your way out from there nothin to that, after it you'll get Greaser Respect +25.
See ya
