Infinte Money
When you go to the loan sharks office, put all of your money in the box in the room.
Go ask him for a loan, once you have recieved this put that in the box as well.
Take all of the money out of the box when you have the amount you desire.
You have to make sure that you have no money in your invenory when you talk to the loan sharks, as long as there is no money in your inventory they don't bother you and will loan you more money.
They never come after you, even though they say they will.