if i am aiming computer eng. then what rank should i look at..... i want nice iit(madras, bombay, delhi, kharagpur etc)

dear balkaran 
you need 60 percent of marks in overall jee advanced paper , 
as jee advanced changes the total marks every year , so, we cannot say anything about marks . 
but try to score rank within 1300-1500 to get those iit , in case no catagory attached on your name . 
REGARDS 
kindly approve