Agreed that you have been invited for personal Interview on the basis of your high percentile but there are others too who have equally scored and might give you fierce competition.
Generally aspirants are invited in ratio of 1:4 on seat availability. Institutes are looking forward a keen observer, adaptable, highly skilled in communication with can do attitude professional in you.
Though you have successfully motivated selection panel till now with your analytical skills but now you need to reaffirm panel’s faith in you and slight deviation of over confidence can be suicidal.
Not only you need to be natural but you have to ensure that your responses are genuine. PI can turn out to be dialogue, provided you are in sync with selection panel’s expectation. Ideally this can be the best scenario.