Link please.
OT I think you should reason with your parents by confronting and yelling at them about how it is ruining your life. If they see how much of an impact it has on you by making you rage they may try and be useful. Even if you have to exaggerate your emotions, do it.
Sounds like that would make the situation worse. Right now it sounds like every time he talks to them they ground him and let his sister do whatever. Well think about it this way. Your sister will grow up to be a spoiled rich bitch who complains when she gets the wrong color car.
You meanwhile will know how to live when you leave the house instead of her who will cry like a loving baby and starve to death because her daddy didn't get her any food and money and she has to work (wahhhh cry me a river salt lake).
And your parents will be put in a retirement home to rot knowing you never said that you loved them because they were horrible parents. Keep thinking about that to get your spirits up!