Only kill 1 Dr.Salvador.
On chapter 4-1, or 4-2 there is a underground room filled with ganados, and a two story room with a Chainsaw man on each floor. Just know that you only have to kill the one on the top floor to get the key, you don't even have to bother the other one. Unless you want an extra 10k then you don't have to fight him.
What I did was just keep shooting the mine thrower in his direction. One mine hit the wall and blew, throwing him back, and letting him know that there was an enemy around. Then he went over to the ladder and just kept walking he didn't go down it, so I shot him in the head with the magnum each time he went over to the ladder.
Then I shot all the other ganados, went over and climbed up the ladder, got the key and went back down, And through the door. The other Chainsaw man had no idea what happened. Then Leon went on an exciting cart ride through the mines.
More tricks, tips and cheats for this game are right here - Resident Evil 4 cheats
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