JEE Advanced maximum are not defined :

Maximum Marks vary every year like below:

2017- 366

2016- 372

2015 - 504

2014 - 360

So, it is difficult to predict marks as exam pattern and marks change every year but you should score more than 50% marks to get good branch in Top IITs.

In 2017, 145 was the cut off to get IITs for general category. 

You can check the cut off rank of IIT Bombay from the given below link

IIT Bombay cut off 

Good Luck!!

The exam pattern of Jee advanced changes every year so it is difficult to provide a marks range but it is advisable to get more than 60% to get seat in top IITs. Also, if you talk about this year, then the opening rank was 1 and CSE branch got closed on 60. For reference, you can go through the below article -

IIT Bombay Cut off 2017

Hope this helps!!!