With a larger throttle body the air loses velocity assuming you're NA. So the throttle response goes down. Assuming that you're throttle body is the most restrictive portion of your intake (which I will bet my car that its not) you will see top end gains.
I have a SR performance twin 62mm.
I only did it because I am about to supercharge.
I did not lose anything, throttle response was the same, or a little better.
I found a guy online whom dyno ran before and after a 62 mm , he claimed 6-7hp gain....... not really worth the money unless your going to boost. IMO