Been to this place at least 5 times now.
Get their authentic pad thai first. None of that kao san road greasy street pad thai, just a huge bowl of real pad thai wrapped in an egg crepe. No ketchup in the authentic pad thai.
Otherwise, get the regular pad thai, which is bigger than Salad King / Kao San Road's portions. I don't get what the hype is about with those places. I would pick Pi Tom's over them!
Anyways, to reiterate;
Do you wanna starve to death? If not, get the authentic pad thai or just the pad thai!