As said above, RacingBrake sells upgrade kits for the NSX.
First, they have a kit to upgrade the 1991-1996 NSX brakes to the 1997+ OEM sizes (298x28mm front, 303x23mm rear).
Seconds, they sell a kit which upgrades your brakes to even larger ones to the sizes 324x28mm front and 330x23mm rear.
You will need 17" wheels or larger to fit them.
I upgraded my front brakes with the 324x28mm kit a couple of years ago and last month upgraded the rears to the 330x23mm sizes.
So far, I like them very much. My car definately brakes better than before (I am using better pads also). Also, these brakes fill up the space under my wheels rather nicely also.